Science

101 Best Science Projects for Students: From Beginner to Advanced

101 science project ideas in chemistry, biology, environmental and Earth science and astronomy, each with a testable question, a method and a way to extend it.

By BlogAI Editors · · 38 min read

The hardest part of a science project is usually choosing one. A good project starts with a question you can test. "Plants" is a topic. "How does salty water affect how many radish seeds germinate?" is a project: you change one thing, measure another, and draw a conclusion from your data.

This list gives you 101 science project ideas in three levels. Each one has a question, a method, the skills it builds, and a way to go further that can turn a class exercise into a strong science fair entry. The projects cover chemistry, biology, environmental science, Earth science, astronomy and data science. Physics projects are collected separately in our 101 physics projects for students.

How to use this list. Projects 1–35 suit beginners and younger students: household materials and simple measurements. Projects 36–70 add quantitative methods, graphs and school-lab equipment. Projects 71–101 use advanced lab techniques, programming or real scientific datasets, and suit senior high school and early university students. A beginner project done carefully, with a control, repeated trials and honest analysis, will impress more than an advanced project done badly.

We have not run each project for this article. The methods follow standard school-lab practice from the OpenStax textbooks, Science Buddies and the data sources linked in each entry, and your results will depend on your materials.

How to plan a science project

Follow these steps before you start collecting data:

  1. Write a testable question in the form "How does X affect Y?"
  2. Identify your variables. The independent variable is what you change. The dependent variable is what you measure. Control variables are everything you keep the same.
  3. Include a control group, a setup where you do not apply the change, to compare against.
  4. Make a hypothesis with a reason, based on what you already know or have read.
  5. Use enough samples. Living things vary, so test at least 10 seeds, leaves or plants per group where you can, and repeat chemistry trials at least three times.
  6. Record everything in a dated lab notebook, including mistakes and changes to your plan.
  7. Analyse honestly. Graph your results, calculate averages and spread, and say whether the difference between groups is larger than the variation within them.

Safety and science fair rules

Science fairs have strict rules for some kinds of projects, and they are updated every year. Under the rules of the Regeneron International Science and Engineering Fair (ISEF), which many regional fairs follow:

  • Human participants: projects that involve surveys, tests or measurements on people, including taste tests and memory tests, usually need approval from an Institutional Review Board before you begin, plus informed consent (Society for Science: Human Participants).
  • Vertebrate animals: experiments on animals with backbones need prior approval and are tightly restricted. Simply watching animals in their natural habitat is usually treated differently, but check the rules (Society for Science: Vertebrate Animals).
  • Microorganisms: growing bacteria or mould, especially unknown ones collected from the environment, is regulated as work with potentially hazardous biological agents. Requirements typically include sealed dishes that are never opened, a qualified supervisor and proper disposal, and many fairs need approval before you start (Society for Science: Potentially Hazardous Biological Agents).
  • Hazardous chemicals: acids, alkalis, flammable solvents and other hazardous substances need a risk assessment and supervision (Society for Science: Hazardous Chemicals, Activities or Devices).

Always check your own fair's current rules with your teacher before starting, because local fairs can be stricter. In this list, projects that involve people, animals, microbes or hazardous chemicals are flagged in the method.

Useful free tools

  • A spreadsheet (Google Sheets, Excel or LibreOffice) for tables, averages and graphs.
  • Python with pandas and Matplotlib for the data projects at the advanced level. Our 101 NumPy examples and pandas tips and tricks cover the basics.
  • Fiji (ImageJ), free image analysis software, for measuring leaf areas, root lengths and colony counts from photos.
  • Citizen-science platforms such as iNaturalist, eBird and Zooniverse, which provide both data and a way to contribute your own.

Beginner projects (1–35)

These use household materials and simple measurements with a ruler, kitchen scale, thermometer or timer.

1. Which antacid neutralises the most acid?

Question: Which brand of antacid tablet neutralises the most vinegar?

Method: Dissolve one tablet of each brand in the same volume of water with red cabbage indicator. Add vinegar a few drops at a time, stirring, and count the drops needed to turn the solution pink. Repeat three times per brand.

Skills: Acids and bases, indicators, fair testing.

Go further: Compare the cost per drop of acid neutralised, and look up each tablet's active ingredient to explain the differences.

2. Which sugar does yeast prefer?

Question: Which sugars can yeast ferment, and which produces gas fastest?

Method: Set up identical bottles with yeast, warm water and equal masses of table sugar, glucose (dextrose), honey, lactose (milk sugar) and no sugar. Fit a balloon to each and measure its circumference every 10 minutes for an hour.

Skills: Respiration, controls, measuring rates.

Go further: Explain why baker's yeast barely ferments lactose, then try lactose-free milk, in which the lactose has already been broken down.

3. Salt and freezing point

Question: How does the amount of salt in water affect the temperature at which it freezes?

Method: Make solutions of 0, 5, 10, 15 and 20 grams of salt per 100 ml of water. Put them in the freezer with a thermometer and record the temperature every 10 minutes until ice forms.

Skills: Solutions, data logging, line graphs.

Go further: Compare table salt with sugar and with calcium chloride de-icer at the same concentrations, and connect your results to road gritting.

4. Keeping cut apples fresh

Question: Which treatment best prevents cut apples from browning?

Method: Cut equal slices and treat them with lemon juice, orange juice, salt water, honey water, plain water and nothing. Photograph them every 30 minutes under the same lighting and rank or score the browning.

Skills: Enzymes, oxidation, scoring scales.

Go further: Use free image analysis software to measure the slices' average colour so your scoring is objective.

5. Does juice lose vitamin C over time?

Question: How much vitamin C does orange juice lose when left open in the fridge?

Method: Make a starch–iodine solution and count how many drops of juice are needed to remove the blue colour. Test fresh juice, then the same carton after one, three and seven days. Adult supervision for iodine.

Skills: Titration-style measurement, time series.

Go further: Compare juice stored at room temperature, in the fridge and heated, to see what speeds up vitamin C breakdown.

6. What makes iron rust fastest?

Question: How do water, salt and vinegar affect how fast steel wool rusts?

Method: Put equal pads of steel wool in jars with tap water, salt water, vinegar, oil and nothing. Weigh them dry at the start and after a week, or photograph and score the rust daily.

Skills: Oxidation, controls, mass measurement.

Go further: Test coatings such as paint, oil and petroleum jelly on nails in salt water, as engineers do when protecting ships and bridges.

7. Crystal size and cooling rate

Question: How does the speed of cooling affect the size of crystals?

Method: Prepare identical saturated solutions of Epsom salts. Cool one in the freezer, one in the fridge, one at room temperature and one in an insulated box. Measure the length of the ten largest crystals in each.

Skills: Solubility, crystallisation, measurement.

Go further: Relate your results to igneous rocks: granite cooled slowly underground and has large crystals, while basalt cooled quickly at the surface and has tiny ones.

8. Which paper towel absorbs the most?

Question: Which brand of paper towel absorbs the most water per sheet and per unit of cost?

Method: Dip one sheet of each brand in water for 10 seconds, let it drip for 30 seconds and measure how much water it absorbed from the change in mass. Repeat five times.

Skills: Measuring by difference, averages, consumer testing.

Go further: Test whether the towel's mass per square centimetre predicts how much it absorbs.

9. Which natural indicator works best?

Question: Which plant extract makes the best pH indicator?

Method: Make extracts of red cabbage, beetroot, blueberries, red onion skins and turmeric. Test each in solutions of known pH (vinegar, lemon juice, water, baking soda, washing soda) and record the colour range.

Skills: Acids and bases, extraction, classification.

Go further: Make indicator paper from your best extract and use it to test household products.

10. Salt and seed germination

Question: How does salty water affect the germination of radish seeds?

Method: Water groups of 20 seeds on damp paper towels with solutions of 0, 0.5, 1, 2 and 4 grams of salt per 100 ml. Count how many germinate each day for a week.

Skills: Osmosis, percentages, dose–response graphs.

Go further: Test seeds of a salt-tolerant crop such as barley, and connect your results to farmland affected by rising salt levels.

11. Light colour and plant growth

Question: How does the colour of light affect how tall seedlings grow?

Method: Grow cress or bean seedlings in boxes lit through red, blue and green coloured film, under white light and in darkness, keeping the light source the same. Measure stem height and leaf colour daily.

Skills: Photosynthesis, controlled variables.

Go further: Explain why green light is less useful to plants, and why many indoor growing lights are red and blue.

12. Does touching plants change how they grow?

Question: Do plants that are brushed every day grow differently from untouched plants?

Method: Grow two groups of identical bean or tomato seedlings. Gently brush one group's stems 20 times a day. After three weeks, compare height, stem thickness and leaf number.

Skills: Plant responses, careful controls.

Go further: Research thigmomorphogenesis, the way plants respond to touch and wind, and why seedlings grown with a fan may be sturdier.

13. Soil type and drainage

Question: How does soil type affect how fast water drains and how much it holds?

Method: Put equal volumes of sand, clay, potting compost and garden soil in funnels lined with filter paper. Pour in the same volume of water and measure how much drains through and how long it takes.

Skills: Soil science, measurement, comparison.

Go further: Grow the same seeds in each soil and see whether drainage predicts plant growth.

14. Light, dark and germination

Question: Do some seeds need light to germinate?

Method: Put 20 seeds of several species (such as lettuce, cress, radish and bean) on damp paper in the light and 20 in a dark box. Count germinated seeds each day.

Skills: Comparative biology, data tables.

Go further: Research why small seeds, such as lettuce, often need light: they must germinate near the surface to reach the light before their food store runs out.

15. Fertiliser and duckweed growth

Question: How does fertiliser concentration affect the growth of duckweed?

Method: Put 10 duckweed plants in each of several cups with different concentrations of liquid plant food in water. Count the fronds every two days for two weeks.

Skills: Population growth, exponential curves.

Go further: Show how too much fertiliser can cause algal blooms in lakes and connect this to farm runoff.

16. How fast do leaves decompose?

Question: Which tree leaves break down fastest in soil?

Method: Put equal masses of dried leaves from different trees into mesh bags. Bury them in the same patch of soil and dig one bag of each type up every two weeks to dry and weigh.

Skills: Decomposition, nutrient cycles, mass loss.

Go further: Compare bags with fine mesh, which keeps out earthworms and insects, against coarse mesh to measure their role.

17. Which bread goes mouldy first?

Question: How do preservatives affect how quickly bread goes mouldy?

Method: Seal slices of shop-bought and home-made or bakery bread in zip-lock bags with a little water. Photograph them daily and record when mould first appears. Never open the bags; dispose of them sealed. Check whether your fair treats this as a microbe project.

Skills: Food science, observation, sealed experiments.

Go further: Read the ingredient labels and research how preservatives such as calcium propionate work.

18. Do natural substances slow mould?

Question: Do garlic, cinnamon, vinegar or honey slow mould growth on bread?

Method: Spread an equal amount of each substance on identical bread slices, with one untreated control, and seal each in a bag. Record daily the percentage of each slice covered in mould. Keep the bags sealed.

Skills: Controls, estimating percentage cover.

Go further: Photograph the slices on a grid to measure the mould area more accurately.

19. How well do people wash their hands?

Question: Which parts of the hands are most often missed when washing?

Method: Use a fluorescent "germ" lotion and an ultraviolet torch, sold for handwashing training. Volunteers apply the lotion, wash as usual, and you photograph the remaining glow. Human participants: get approval and consent.

Skills: Data from people, hygiene science.

Go further: Test whether showing people a handwashing poster changes the result.

20. Does colour change how sweet food tastes?

Question: Do people rate a drink as sweeter when it is coloured red?

Method: Prepare identical sugar solutions, some with red food colouring and some with green or none. Ask volunteers to rate their sweetness without telling them they are the same. Human participants: get approval and consent, and check for allergies.

Skills: Blind testing, rating scales, bias.

Go further: Repeat with volunteers blindfolded to separate the effect of colour from any real difference.

21. Eye dominance and handedness

Question: Are right-handed people usually right-eye dominant?

Method: Test volunteers' eye dominance with the hand-triangle test and record which hand they write with. Collect at least 50 people. Human participants: approval and consent needed.

Skills: Surveys, two-way tables, percentages.

Go further: Add foot dominance (which foot kicks a ball) and see whether all three tend to match.

22. Which sunscreen blocks the most UV?

Question: Do sunscreens with a higher SPF block more ultraviolet light?

Method: Use UV-sensitive beads, which change colour in ultraviolet light. Cover groups of beads with clear plastic film spread with equal amounts of different sunscreens, and put them in sunlight. Compare the colour change against uncovered beads.

Skills: Ultraviolet light, product testing.

Go further: Test whether sunscreen loses effectiveness after being left in a hot car or past its expiry date.

23. Do cheap sunglasses block UV?

Question: How well do sunglasses of different prices block ultraviolet light?

Method: Put UV beads behind each pair of sunglasses in direct sunlight, with an uncovered control, and score the colour change.

Skills: Comparison testing, evaluating claims.

Go further: Compare lenses labelled "UV400" with unlabelled ones.

24. Which materials filter water best?

Question: Which combination of sand, gravel, charcoal and cloth makes muddy water clearest?

Method: Build filters in cut plastic bottles with different layers. Pour the same muddy water through each and measure clarity by how far down a jar of the filtered water you can see a printed mark. Do not drink the water.

Skills: Separation, engineering design.

Go further: Explain why filtration alone does not make water safe to drink, and what water treatment works add.

25. Does mulch keep soil moist?

Question: How do different mulches affect how quickly soil dries out?

Method: Fill pots with the same soil and water them equally. Cover them with bark, straw, grass clippings, gravel or nothing. Weigh them daily for a week to track water loss.

Skills: Evaporation, measuring by mass, gardening science.

Go further: Measure soil temperature under each mulch on a hot day.

26. Where is the air dustiest?

Question: Where around your home or school does the most airborne dust settle?

Method: Hang cards smeared with petroleum jelly in several locations for a week. Count particles in a marked square under a magnifying glass or microscope.

Skills: Sampling, environmental monitoring.

Go further: Repeat in different seasons, and compare with official air-quality data for your area from your national monitoring service.

27. How accurate is the weather forecast?

Question: How often does the forecast correctly predict rain at your home?

Method: Build a rain gauge and record rainfall every day for a month or more. Each evening, record the next day's forecast chance of rain. Compare the two.

Skills: Probability, data collection, verification.

Go further: Check calibration: on days given a 30 percent chance of rain, did it rain on about 30 percent of them?

28. Moon phases and rise times

Question: How do the Moon's shape and the time it rises change through a month?

Method: Observe the Moon every clear evening for six weeks. Record its shape, position, direction and the time you saw it, and compare with an almanac.

Skills: Astronomical observation, patterns.

Go further: Make a model with a lamp and a ball to explain the phases you recorded.

29. Light pollution survey

Question: How does the number of visible stars change from the centre of your town to its outskirts?

Method: On clear, moonless nights, count the stars visible in a chosen constellation at several locations, using the Globe at Night method and reference charts (Globe at Night). Adult for night-time trips.

Skills: Field surveys, mapping.

Go further: Map your results against the brightness of street lighting nearby.

30. Bird feeder preferences

Question: Which types of seed attract which birds?

Method: Put out feeders with different seeds in the same area and count visits by species for 20 minutes at the same time each day. This is observation only; do not handle birds.

Skills: Animal behaviour, identification, tallies.

Go further: Submit your counts to a citizen-science project such as eBird or Project FeederWatch.

31. How does temperature affect dissolving?

Question: How does water temperature affect the time a sugar cube takes to dissolve?

Method: Drop sugar cubes into water at five temperatures between 10 and 70 °C without stirring and time them. Repeat three times. Adult for hot water.

Skills: Rates, graphing, particle theory.

Go further: Compare sugar cubes with granulated sugar to separate the effects of temperature and surface area.

32. Do "biodegradable" bags break down?

Question: Do bags labelled biodegradable or compostable break down faster in soil than ordinary plastic?

Method: Bury equal squares of different bags and of paper in soil. Dig them up after four, eight and twelve weeks and measure their area and mass.

Skills: Materials, decomposition, evaluating labels.

Go further: Repeat in a warm compost heap and compare.

33. Surface area and evaporation

Question: How does the surface area of water affect how fast it evaporates?

Method: Put the same volume of water in containers of different widths. Weigh them every day for a week and calculate the loss per day.

Skills: Water cycle, measuring rates.

Go further: Add a fan or move the containers to the sun to explore other factors.

34. Acid and seashells

Question: How does the acidity of water affect how quickly seashells dissolve?

Method: Put shells of equal mass into vinegar diluted to several strengths and into water. Dry and weigh them after one, three and seven days.

Skills: Acids and carbonates, dilutions, mass loss.

Go further: Connect your results to ocean acidification and its effect on shellfish and corals (NOAA).

35. Which leaves do snails prefer?

Question: Do garden snails prefer some plant leaves over others?

Method: Put equal-sized leaf discs from several plants in a ventilated box with a few snails, and measure the area eaten after 24 hours. Release the snails where you found them.

Skills: Animal behaviour, measuring area, ethics.

Go further: Test whether leaves with a bitter taste or hairy surface are eaten less.

Intermediate projects (36–70)

These involve more precise measurement, dose–response experiments, school-lab equipment or simple statistics.

36. How acidic is vinegar?

Question: Do different vinegars contain the amount of acetic acid stated on the label?

Method: Add excess baking soda to a measured mass of each vinegar on a scale and record the mass lost as carbon dioxide escapes. Use the reaction equation to calculate the acetic acid content.

Skills: Stoichiometry, quantitative chemistry.

Go further: Check your method with a school-lab titration against sodium hydroxide under supervision.

37. Concentration and reaction rate

Question: How does acid concentration affect the rate of a reaction?

Method: In a school lab, react equal pieces of magnesium ribbon with hydrochloric acid at several concentrations and time how long they take to disappear, or collect the gas in an upturned measuring cylinder. Supervised: hazardous chemicals.

Skills: Rates, collision theory, graphing.

Go further: Plot rate against concentration and determine the order of the reaction.

38. Enzymes and temperature

Question: How does temperature affect the activity of the enzyme catalase?

Method: Blend potato with water and filter it to make an enzyme extract. Mix it with 3 percent hydrogen peroxide at five temperatures and measure the volume of oxygen produced in one minute, or the height of the foam.

Skills: Enzyme kinetics, optimum temperature.

Go further: Find the temperature at which activity peaks and explain why it falls at higher temperatures.

39. Enzymes and pH

Question: How does pH affect catalase activity?

Method: Use the same potato extract with buffers or diluted vinegar and baking soda solutions at several measured pH values, and measure oxygen produced.

Skills: pH, enzyme structure, controlled variables.

Go further: Compare catalase from different sources such as liver, yeast and potato.

40. Stopping the browning enzyme

Question: Which substances best inhibit browning of cut fruit?

Method: Treat cut apple with solutions of citric acid, ascorbic acid, salt and sugar at several concentrations. Measure colour change over time with a phone colour-picker app or image analysis.

Skills: Enzyme inhibition, image analysis.

Go further: Find the lowest concentration of each that works, which is what food manufacturers want to know.

41. Protease enzymes in fruit

Question: How does heating fresh pineapple affect its ability to stop gelatin setting?

Method: Heat samples of fresh pineapple juice to 40, 60, 80 and 100 °C for five minutes. Add each to gelatin, refrigerate, and test whether and how firmly it sets.

Skills: Enzymes, denaturation, food science.

Go further: Test kiwi fruit, papaya and mango, and research which contain protein-digesting enzymes.

42. Finding the concentration of a potato

Question: At what salt or sugar concentration does potato tissue neither gain nor lose water?

Method: Weigh potato cylinders, soak groups in six sugar solutions between 0 and 1 mol/L for 24 hours, then reweigh. Plot percentage change in mass against concentration and find where the line crosses zero.

Skills: Osmosis, interpolation, percentage change.

Go further: Compare potato with sweet potato and carrot.

43. Light intensity and photosynthesis

Question: How does light intensity affect the rate of photosynthesis?

Method: Use the floating leaf disc method with a lamp at five distances. Record the time for half the discs to float, and repeat each distance three times.

Skills: Photosynthesis, rates, inverse relationships.

Go further: Use a phone light-meter app to measure light intensity directly rather than relying on distance.

44. Carbon dioxide and photosynthesis

Question: How does the concentration of dissolved carbon dioxide affect the rate of photosynthesis?

Method: Use the leaf disc method with baking soda solutions from 0 to 1 percent, keeping light constant. Measure the time for half the discs to float.

Skills: Limiting factors, dose–response.

Go further: Explain why greenhouses sometimes add carbon dioxide to boost crop growth.

45. Build a potometer

Question: How do wind and humidity affect how fast a plant loses water?

Method: Connect a leafy shoot to a water-filled syringe or capillary tube, sealing the joint with petroleum jelly. Measure how far an air bubble moves per minute in still air, in front of a fan and inside a clear plastic bag.

Skills: Transpiration, apparatus design.

Go further: Cover the top or bottom surfaces of leaves with petroleum jelly to find where most water is lost.

46. Sun leaves and shade leaves

Question: Do leaves growing in sun have more stomata than leaves in shade?

Method: Take nail-polish impressions from the undersides of 10 sun leaves and 10 shade leaves from the same tree. Count stomata in a fixed field of view under a microscope.

Skills: Microscopy, sampling, comparing means.

Go further: Use a t-test to judge whether the difference is statistically significant.

47. Yeast respiration and temperature

Question: How does temperature affect the rate of respiration in yeast?

Method: Put yeast and sugar solution in test tubes in water baths at five temperatures and collect the carbon dioxide in an upturned measuring cylinder, or count bubbles from a delivery tube, over 10 minutes.

Skills: Respiration, water baths, rates.

Go further: Model the results with a curve and estimate the optimum temperature.

48. Making yoghurt with different milks

Question: How quickly does pH fall in yoghurt made from different milks?

Method: Inoculate cow's milk, goat's milk and plant milks with the same live yoghurt and keep them at 43 °C. Measure pH with indicator paper or a pH meter every hour. Adult for heating.

Skills: Fermentation, time series, food microbiology.

Go further: Explain your results using the sugar and protein content on each milk's label.

49. Do spices stop bacteria growing?

Question: Which spice extracts most inhibit bacterial growth?

Method: In a school lab, spread a known, non-pathogenic bacterium (such as a BSL-1 teaching strain from a biological supplier) on agar plates. Add paper discs soaked in spice extracts and measure the clear zones after incubation, keeping plates sealed. Microorganisms: supervision and prior approval needed.

Skills: Microbiology, aseptic technique, zone measurement.

Go further: Compare the extracts with a dilution series to find the lowest effective concentration.

50. Soap vs hand sanitiser

Question: Does soap or alcohol hand sanitiser reduce the microbes on hands more?

Method: Volunteers press fingertips onto agar plates before and after washing with soap or using sanitiser. Seal the plates, incubate them at room temperature and count colonies without opening. Microorganisms and human participants: approval needed.

Skills: Experimental design, colony counting.

Go further: Test how long the effect lasts by sampling again after 30 and 60 minutes.

51. Ultraviolet light and yeast survival

Question: How does exposure time to ultraviolet light affect yeast survival?

Method: Spread dilute baker's yeast on agar plates, expose them to a UV lamp for different times with lids removed under supervision, then replace lids and incubate. Count colonies. Supervised: never look at the UV lamp and protect skin.

Skills: Dilution, survival curves, DNA damage.

Go further: Test whether sunscreen on a clear film over the plate protects the yeast.

52. Water quality in a local stream

Question: How does water quality change along a stream, upstream and downstream of a town or farm?

Method: Use test kits to measure pH, nitrate, phosphate, dissolved oxygen and temperature at several points on the same day. Repeat monthly. Adult for fieldwork near water.

Skills: Field sampling, water chemistry, mapping.

Go further: Compare your results with official monitoring data and research what might cause differences.

53. Stream insects as pollution indicators

Question: Does the variety of invertebrates in a stream match its chemical water quality?

Method: Use a kick net to sample invertebrates at several sites, identify them with a key and calculate a biotic index based on which pollution-sensitive groups, such as mayfly and stonefly nymphs, are present. Return them to the water.

Skills: Ecology, identification, indices.

Go further: Compare your index with chemical results from project 52.

54. Microplastics in beach sand

Question: How many microplastic particles are found in sand from different parts of a beach?

Method: Mix sand samples with very salty water, let the sand settle, and filter the floating material. Count and classify particles under a microscope. Use cotton clothing and covered containers to avoid contaminating your samples with fibres.

Skills: Density separation, contamination control.

Go further: Include "blank" samples with no sand to measure contamination from the air and your equipment.

55. Soil pH and plant growth

Question: How does soil pH affect the growth of radish plants?

Method: Adjust pots of the same soil with garden lime or sulphur to several pH values, measured with a soil test kit. Grow radishes in each and measure their mass after four weeks.

Skills: Soil chemistry, plant growth.

Go further: Research which plants prefer acidic soil and why.

56. Duckweed as a pollution test

Question: At what concentration does washing-up liquid harm duckweed?

Method: Grow duckweed in a dilution series of detergent (for example 0, 0.01, 0.1, 1 and 10 ml per litre). Count fronds every two days for two weeks and calculate the growth rate.

Skills: Ecotoxicology, dilutions, logarithmic scales.

Go further: Estimate the concentration that halves growth, a standard measure called the EC50.

57. Do some plants poison their neighbours?

Question: Do extracts of black walnut, eucalyptus or pine leaves reduce seed germination?

Method: Soak crushed leaves in water, filter the extracts, and use them to water groups of lettuce seeds. Compare germination and root length with seeds watered with plain water.

Skills: Allelopathy, controls.

Go further: Make a dilution series to see how strong the effect is.

58. Compost and plant growth

Question: How does the proportion of compost in soil affect plant growth?

Method: Grow the same seedlings in mixtures of 0, 10, 25, 50 and 100 percent compost. Measure height and dry mass after five weeks.

Skills: Soil fertility, dry mass measurement.

Go further: Add biochar (charcoal made for soil) as another treatment.

59. Urban heat island

Question: How much warmer is the centre of your town than its outskirts?

Method: On a calm evening, record air temperature with the same thermometer at fixed points along a route from the outskirts to the centre, noting the time. Repeat on several evenings. Adult for fieldwork.

Skills: Microclimate, mapping, controlling for time.

Go further: Relate the temperatures to the amount of green space or paving at each point.

60. How much carbon is in a tree?

Question: How much carbon is stored in the trees in your school grounds?

Method: Measure each tree's trunk circumference at 1.3 m above the ground, identify the species and use a published allometric equation to estimate its mass and carbon content.

Skills: Field measurement, using published equations.

Go further: Estimate how much carbon dioxide the trees would remove in a year and compare it with your school's energy use.

61. Biodiversity in lawns and meadows

Question: Does an unmown area of grass have more plant species than a mown lawn?

Method: Throw a 0.5 m by 0.5 m square frame (a quadrat) at random 10 times in each area. Identify and count the plant species in each and calculate a diversity index.

Skills: Random sampling, diversity indices.

Go further: Count insects in each area too, to see whether plant diversity supports animal diversity.

Question: How do the birds you see compare with long-term records for your area?

Method: Do regular timed bird counts in one location and submit them to eBird (eBird). Compare your counts with eBird's records for the same area and season.

Skills: Standardised surveys, citizen science.

Go further: Look for species whose arrival dates in spring seem to be changing.

63. Flower colour and pollinators

Question: Do bees and other pollinators prefer flowers of particular colours?

Method: Watch patches of flowers of different colours for 10 minutes each at the same times of day, recording each visit by insect type.

Skills: Behavioural observation, chi-squared test.

Go further: Make artificial flowers from coloured card with a drop of sugar water to control for scent.

64. Identify food dyes by chromatography

Question: Which dyes are in coloured sweets?

Method: Dissolve the coating of sweets in a drop of water and run paper chromatography alongside known food colourings. Calculate RfR_f values, the distance each dye travels divided by the distance the water travels.

Skills: Chromatography, identification, measurement.

Go further: Compare your results with the ingredients listed on the packaging.

65. Electrolysis of water

Question: How does the concentration of electrolyte affect the rate of gas production in electrolysis?

Method: Use a 9 V battery and two pencil leads or stainless-steel electrodes in water with different amounts of baking soda or Epsom salts dissolved. Collect gas over a set time in upturned tubes. Do not use table salt, which can produce chlorine. Adult supervision.

Skills: Electrochemistry, gas collection.

Go further: Check that you collect roughly twice as much hydrogen as oxygen, and explain why.

66. Make bioplastic from starch

Question: How does the amount of glycerol affect the flexibility and strength of starch plastic?

Method: Make films from cornflour, water, vinegar and different amounts of glycerol, heated until thick and dried in moulds. Test each film's stretch and the mass it can hold before tearing. Adult for heating.

Skills: Polymers, materials testing.

Go further: Bury samples to compare how quickly they break down with ordinary plastic.

67. Natural dyes and colourfastness

Question: Which mordant makes natural dyes most resistant to washing?

Method: Dye cotton strips with onion skins, turmeric or red cabbage, after pre-treating them with alum, iron (from rusty nails soaked in vinegar), salt or nothing. Wash them repeatedly and score the fading.

Skills: Chemistry of dyes, scoring, controls.

Go further: Test how sunlight affects fading.

68. Supersaturation and crystal growth

Question: How does the concentration of a solution affect how fast a crystal grows?

Method: Hang seed crystals of alum or Epsom salts in solutions of different concentrations at constant temperature. Weigh them every day.

Skills: Solubility curves, growth rates.

Go further: Plot a solubility curve for the salt from your own measurements.

69. Which fruit yields the most DNA?

Question: Which fruits give the most DNA per gram?

Method: Extract DNA from equal masses of strawberry, banana, kiwi and onion using the same method. Collect and dry the DNA on pre-weighed filter paper and compare masses. Adult for rubbing alcohol.

Skills: Standardised methods, extraction.

Go further: Explain your results using chromosome numbers and cell sizes: strawberries have eight copies of each chromosome.

70. Sleep and memory

Question: Do students who sleep longer remember a list of words better?

Method: Volunteers record their sleep for several nights, then learn a word list and are tested an hour later. Look for a relationship between average sleep and score. Human participants: approval and consent needed.

Skills: Correlation, survey design, ethics.

Go further: Discuss why your study cannot prove that sleep causes better memory, and how an experiment could.

Advanced projects (71–101)

These use advanced lab techniques, electronics, programming or real scientific datasets.

Question: How have temperature and rainfall changed at your nearest long-running weather station?

Method: Download daily or monthly records from NOAA's Climate Data Online (NOAA NCEI) or your national weather service. Calculate annual averages and fit a trend line.

Skills: Data cleaning, time series, regression.

Go further: Count days above a threshold temperature each decade, and test whether extremes are changing faster than averages.

72. The breathing planet

Question: How does the seasonal swing in carbon dioxide vary with latitude?

Method: Download monthly carbon dioxide records from NOAA's monitoring stations from the Arctic to the South Pole (NOAA GML). Remove the long-term trend and measure the size of the seasonal cycle at each station.

Skills: Detrending, comparing datasets.

Go further: Explain the differences using the distribution of land and forests between the hemispheres.

73. Earthquake statistics

Question: Do earthquakes follow the Gutenberg–Richter law, with about ten times fewer quakes for each step up in magnitude?

Method: Download a year of earthquakes from the USGS catalogue (USGS), count events per magnitude band and plot the logarithm of the count against magnitude.

Skills: Logarithmic plots, power laws.

Go further: Compare the slope of the line for different regions.

74. The exoplanet size gap

Question: Are there fewer planets of about 1.5 to 2 times Earth's radius than of sizes just above and below?

Method: Download confirmed planets from the NASA Exoplanet Archive (NASA) and plot a histogram of planet radius on a logarithmic scale.

Skills: Histograms, selection bias.

Go further: Research the "radius valley" and the theories proposed to explain it.

75. Find a planet's transit

Question: Can you detect a known exoplanet in space-telescope data and measure its size?

Method: Use the free Python package Lightkurve (Lightkurve) to download a TESS or Kepler light curve of a known planet host. Flatten and fold it to find the transit, and estimate the planet's radius from the depth of the dip.

Skills: Python, signal processing, astrophysics.

Go further: Search a star with no known planets and assess how small a planet you could have detected.

76. Galaxy shapes and colours

Question: Are spiral galaxies bluer than elliptical galaxies?

Method: Use classified galaxy data from Galaxy Zoo, a Zooniverse project (Zooniverse), together with the galaxies' colours from its published data releases, and compare the colour distributions.

Skills: Large datasets, comparison of distributions.

Go further: Explain your result in terms of star formation: blue light comes from young, hot stars.

77. Are species moving north?

Question: Has the range of a chosen species shifted over the last few decades?

Method: Download occurrence records for a well-recorded species, such as a butterfly or bird, from GBIF (GBIF). Compare the latitudes of records in two time periods, accounting for changes in how much recording was done.

Skills: Biodiversity data, sampling bias.

Go further: Compare species that prefer warm and cool climates.

78. Is spring arriving earlier?

Question: Are plants in your region leafing out or flowering earlier than in the past?

Method: Download plant phenology records from the USA National Phenology Network (USA-NPN) or a similar national scheme, and compare first-flowering dates with spring temperatures.

Skills: Phenology, correlation, climate links.

Go further: Record your own observations of local plants and submit them.

79. Vegetation change from space

Question: How has the vegetation around your town changed over the past decade?

Method: Use free satellite imagery from Copernicus Sentinel-2 (Copernicus Browser) or Landsat (USGS EarthExplorer) to calculate NDVI, a vegetation index from red and near-infrared light, for the same season in different years.

Skills: Remote sensing, image analysis.

Go further: Validate your results by visiting sites and photographing what is actually there.

80. Test a low-cost air sensor

Question: How accurate is a low-cost particle sensor compared with an official air-quality monitor?

Method: Connect a low-cost PM2.5 sensor to an Arduino or Raspberry Pi and log readings beside, or near, an official monitoring station. Compare your data with the station's published readings.

Skills: Electronics, calibration, regression.

Go further: Test how humidity affects the sensor's errors and build a correction.

81. Build a colorimeter

Question: Does a homemade colorimeter follow the Beer–Lambert law?

Method: Build a colorimeter from an LED, a light sensor and a microcontroller. Measure how much light passes through food-dye solutions of known concentrations, plot absorbance against concentration, and test whether it gives a straight line.

Skills: Instrument design, calibration curves.

Go further: Use your calibration curve to find the dye concentration in a sports drink.

82. Phosphate in local water

Question: How much phosphate is in local streams, ponds or tap water?

Method: Use a colorimetric phosphate test kit with your colorimeter from project 81, calibrated with standards of known concentration, and sample several sites. Supervised for reagents.

Skills: Analytical chemistry, calibration.

Go further: Relate phosphate levels to algae growth or land use around each site.

83. Finding a rate law

Question: What is the order of reaction for the fading of crystal violet in alkaline solution?

Method: In a school lab, mix crystal violet with sodium hydroxide and measure the colour over time with a colorimeter. Plot concentration, its logarithm and its reciprocal against time to see which gives a straight line. Supervised: hazardous chemicals.

Skills: Kinetics, graphical analysis.

Go further: Repeat at several temperatures and calculate the activation energy using the Arrhenius equation.

84. Compare catalysts

Question: Which is the most effective catalyst for decomposing hydrogen peroxide: manganese dioxide, iron(III) ions, yeast or potato?

Method: Measure the volume of oxygen produced per minute with each catalyst, using the same peroxide concentration and temperature, and repeat with different catalyst amounts. Supervised.

Skills: Catalysis, gas collection, rate comparison.

Go further: Check whether each catalyst is unchanged at the end by recovering and reusing it.

85. How fast do bioplastics degrade?

Question: How do temperature and moisture affect the breakdown of compostable plastics?

Method: Put weighed pieces of PLA cups and starch-based bags in compost kept at different temperatures, for example a heated propagator and room temperature. Weigh and photograph them every two weeks.

Skills: Materials science, long-term experiments.

Go further: Compare your results with the conditions described in compostability standards.

86. Build an evolutionary tree from DNA

Question: Do DNA sequences group animals the same way as their body features do?

Method: Download the same gene, such as cytochrome c oxidase I, for 10 to 20 species from NCBI (NCBI BLAST). Align the sequences and build a tree with free software such as MEGA, then compare it with traditional classification.

Skills: Bioinformatics, phylogenetics.

Go further: Find a case where DNA disagrees with appearance and research why.

87. How confident is AlphaFold?

Question: Which kinds of proteins does AlphaFold predict with low confidence?

Method: Download predicted structures from the AlphaFold Protein Structure Database (AlphaFold DB) for a set of human proteins, and compare their per-residue confidence scores (pLDDT) with which regions are known to be disordered.

Skills: Structural biology, data analysis.

Go further: Compare a prediction with an experimental structure from the Protein Data Bank.

88. Simulate antibiotic resistance

Question: How does the dose and length of an antibiotic course affect the spread of resistance in a population?

Method: Write a simple computer model in Python in which bacteria divide, mutate and die depending on the antibiotic concentration. Run it many times with different treatment plans and compare outcomes.

Skills: Modelling, natural selection, simulation.

Go further: Compare your model's conclusions with published research, and discuss its simplifications honestly.

89. Model an epidemic

Question: How well does an SIR model fit a real outbreak?

Method: Program a susceptible-infected-recovered model and fit its parameters to publicly available case data for an outbreak, such as seasonal flu surveillance data from a public health agency.

Skills: Differential equations, curve fitting.

Go further: Add vaccination to the model and estimate the coverage needed to stop spread.

90. Gel electrophoresis of dyes

Question: Can electrophoresis separate food dyes by charge and size?

Method: In a school lab, make an agarose gel and run food dyes through it with an electrophoresis kit. Measure how far each dye moves.

Skills: Electrophoresis, a core technique in DNA analysis.

Go further: Run the gel at different voltages and explain how this affects separation.

91. Fruit fly genetics

Question: Do crosses between wild-type and mutant fruit flies give the ratios Mendel's laws predict?

Method: Buy wild-type and mutant Drosophila from a biological supplier. Cross them, then cross the offspring, and count the traits in the second generation. Use a chi-squared test to compare with predictions.

Skills: Genetics, statistics, handling live organisms.

Go further: Use a sex-linked trait, such as white eyes, to reproduce Thomas Hunt Morgan's discovery.

92. Planarian regeneration

Question: How does temperature affect how quickly flatworms regenerate?

Method: Cut planarian flatworms from a supplier into halves under supervision and keep groups at different temperatures. Photograph them daily and record when eyespots and heads reappear.

Skills: Regeneration, developmental biology, time series.

Go further: Research the stem cells, called neoblasts, that make regeneration possible.

93. Water fleas and heart rate

Question: How does temperature affect the heart rate of Daphnia?

Method: Place a water flea in a drop of water under a microscope at different temperatures and count heartbeats in 15 seconds, filming to count accurately. Use the animals as briefly as possible and return them to their culture.

Skills: Physiology, microscopy, ethics.

Go further: Compare species from warm and cold water, or test caffeine at very low concentrations.

94. Mud batteries

Question: How does the organic content of soil affect the electricity produced by a microbial fuel cell?

Method: Build microbial fuel cells from kits or containers with carbon-felt electrodes buried in mud, adding different amounts of organic matter. Log voltage across a resistor for several weeks. Keep the cells closed and follow your fair's rules for environmental microbes.

Skills: Microbiology, electrochemistry, data logging.

Go further: Calculate power output and compare it with what a small sensor would need.

95. Growing algae for fuel

Question: How do light and nutrients affect the growth rate of microalgae?

Method: Grow Chlorella cultures from a supplier in bottles with aquarium bubblers at different light levels and nutrient concentrations. Measure cloudiness daily with your colorimeter or by counting cells.

Skills: Microbial growth curves, photosynthesis.

Go further: Estimate the oil yield your best culture could produce per square metre.

96. Warming and soil respiration

Question: How does temperature affect the rate at which soil microbes release carbon dioxide?

Method: Seal equal samples of moist soil in jars with a carbon dioxide sensor or with a dish of limewater, at several temperatures. Measure carbon dioxide build-up over a few days.

Skills: Soil biology, climate feedbacks.

Go further: Calculate how much the rate increases for each 10 °C rise, a value known as Q10.

97. Measure water hardness by titration

Question: How does water hardness vary between tap water, bottled water and local springs?

Method: In a school lab, titrate water samples with EDTA using an indicator such as Eriochrome Black T to measure calcium and magnesium. Supervised.

Skills: Complexometric titration, precision.

Go further: Compare your results with the values published by your water supplier or on bottle labels.

98. Identify birds by their songs

Question: Can a machine learning model learn to tell bird species apart from their songs?

Method: Download recordings of a few species from the Xeno-canto archive (Xeno-canto), convert them into spectrograms, and train a classifier. Test it on recordings it has not seen.

Skills: Machine learning, audio processing.

Go further: Test your model on your own recordings from outside, and analyse which species it confuses.

99. Automated cell counting

Question: How accurately can image analysis software count cells or colonies compared with a human?

Method: Photograph yeast cells in a counting chamber, or sealed colony plates, and count them by hand and with Fiji's automatic particle analysis (Fiji). Compare the counts and find where the software goes wrong.

Skills: Image analysis, measurement error.

Go further: Adjust the software's settings to improve agreement and report the remaining error.

Question: How fast is sea level rising along different coastlines?

Method: Download tide-gauge records from NOAA (NOAA Tides and Currents) for several locations and calculate trends. Compare places where the land itself is rising or sinking.

Skills: Long-term data, regression, geology.

Go further: Compare your trends with satellite measurements of global sea level.

101. Ocean pH over time

Question: How fast is the open ocean becoming more acidic?

Method: Download measurements from the Hawaii Ocean Time-series, which has sampled seawater near Hawaii since 1988 (HOT). Plot pH and dissolved carbon dioxide over time and compare the trend with atmospheric carbon dioxide at Mauna Loa.

Skills: Ocean chemistry, comparing datasets.

Go further: Use project 34's shell experiment to show what the change in pH means for shell-building organisms.

Writing up and presenting your project

Judges and teachers look for the same things:

  • A clear question and hypothesis, stated at the start.
  • A method someone else could repeat, with photos or diagrams and a list of materials.
  • A control group and enough samples, with the number of repeats stated.
  • Raw and processed data in tables with units.
  • Graphs with labelled axes, showing averages and the spread of the data.
  • An honest conclusion that answers the question without claiming more than the data shows.
  • An evaluation of weaknesses in the method and what you would improve.
  • References for background information, methods and data sources.

Common mistakes

  • No control group, so there is nothing to compare against.
  • Too few samples. One plant per group cannot tell you whether a difference is real.
  • Changing more than one thing at a time.
  • Claiming cause from a correlation, especially in survey projects.
  • Starting before getting approval for projects that involve people, animals or microbes.

Where to go next

References

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