Science Fair Project Ideas by Grade (K–8), with a Fair-Test Planner

Science fair season usually lands between January and March. For a lot of families, it starts with one question at the kitchen table: “What should I do?”

This guide is for teachers and parents. It has project ideas sorted by grade, a planner students can copy, a frame for writing the conclusion, a simple rubric, and a timeline that starts six weeks out. Want it all as printable pages with room to write? Download the free Science Fair Planner.

What makes a good science fair project

A good project has four things:

A question you can test. “Which paper towel soaks up the most water?” is testable. “How do paper towels work?” is not, at least not in a weekend.
One thing changed. Change the brand of paper towel. Keep the size, the water and the timing the same.
Something measured. Millilitres, centimetres, seconds, grams. A number beats “it looked like more.”
Repeated trials. Do it at least three times. Things never come out exactly the same twice, and repeating shows whether a difference is real.

Demo or experiment?

A demo shows something that is already known. The baking soda volcano is a demo: it fizzes every time, and nothing is being tested.

An experiment asks a question and lets the answer surprise you. “Does warmer vinegar make the volcano fizz higher?” turns the same volcano into an experiment. You change one thing, measure, and repeat.

Judges almost always prefer an experiment. It doesn’t have to be fancy. A simple question tested carefully beats a dramatic demo every time.

Project ideas by grade

Every idea below uses household or dollar-store materials and is safe at home with an adult nearby. Costs are rough, in dollars, and assume you already have basics like cups, tape and a ruler. Where one of our lessons covers the same science, it’s linked.

Kindergarten to Grade 2

At this age, keep it to one question and a simple count or measurement. An adult can do the writing; the child does the looking, the counting and the deciding.

Which ball bounces highest? Change: the kind of ball (tennis, rubber, foam). Measure: bounce height against a paper strip taped to the wall, dropped from 1 m (3 ft). Cost: about $0.
Which paper towel soaks up the most water? Change: the brand. Measure: how many spoonfuls of water one sheet soaks up before it drips. Cost: about $5.
Do seeds need water to sprout? Change: wet or dry paper towel in a zip-top bag. Measure: how many of 10 bean seeds sprout in 5 days. Cost: about $3. See What’s inside a seed?
Is my shadow longer in the morning? Change: the time of day. Measure: the length of a bottle’s shadow on the same spot at 9 a.m., noon and 3 p.m. Cost: about $0. See Why is my shadow long in the morning?
What can light go through? Change: the material (tissue paper, wax paper, foil). Measure: how many layers it takes before a flashlight spot disappears on the wall. Cost: about $3. See What can light go through?
Does a tight string make a cup phone work better? Change: tight or loose string. Measure: how many of 5 whispered words the listener gets right. Cost: about $2. See Can a string carry your voice?
Does a higher ramp make a toy car go farther? Change: ramp height (1, 2 or 3 books). Measure: how far the car rolls past the end of the ramp. Cost: about $0.
Does salt make ice melt faster? Change: salt or no salt on an ice cube. Measure: minutes until each cube is gone. Cost: about $0.
Which wrap keeps an ice cube frozen longest? Change: a wool sock, foil or nothing. Measure: minutes until each cube melts. Many kids expect the sock to warm the ice. It does the opposite, which makes a great surprise. Cost: about $0.

Grades 3 to 5

Students can now plan most of the test themselves, take three to five trials and work out an average.

Do longer wings make a paper helicopter fall slower? Change: wing length. Measure: fall time from the same height, five drops each. Cost: about $0. See Why do scientists repeat their tests?
Which floor makes a ball stop soonest? Change: the surface (hard floor, carpet, towel). Measure: how far the ball rolls from the same ramp. Cost: about $0. See Why does a ball stop rolling?
Do more magnets pull through more cards? Change: one, two or three fridge magnets stacked. Measure: how many playing cards fit between magnet and paper clip before the clip drops. Cost: about $5. See Can a magnet work through a table?
What makes a wet towel dry fastest? Change: where it dries (indoors, shaded outside or in the sun). Measure: grams lost on a kitchen scale every 15 minutes. Cost: about $0 with a scale you have. See Where does a puddle go?
Is my writing hand faster? Change: writing hand or other hand. Measure: where you catch a dropped ruler, in centimetres. Ten catches each. Cost: about $0. See How fast are our reaction times?
Which paper plane flies farthest? Change: the fold design. Measure: distance with a tape measure, same thrower, three throws each. Cost: about $0. See What makes a paper plane fly farthest?
Does more air make a balloon rocket go farther? Change: number of breaths into the balloon. Measure: distance along a string. Cost: about $3. See How does a rocket push itself into space?
Where is the warmest spot in the yard? Change: the location (sun, shade, beside a wall). Measure: air temperature at the same height and the same time. Cost: about $5 for a thermometer. See Is it hotter by the slide?
Does a bean plant grow taller in sun or shade? Change: a sunny window or a dim corner. Measure: height in millimetres every two days for two to three weeks. Start early. Cost: about $5.
Does sugar dissolve faster in warm water? Change: cold, room-temperature or warm tap water (an adult runs the tap). Measure: seconds until a sugar cube is gone, stirred the same way. Cost: about $3.

Grades 6 to 8

Older students should control several variables, take at least five trials, graph their results and explain the science behind them.

Which material keeps ice frozen longest? Change: the insulation (foil, newspaper, felt, bubble wrap). Measure: mass of ice left after one hour, in grams. Cost: about $5. See Can you keep an ice cube frozen the longest?
How does temperature change the air in a bottle? Change: ice water, room temperature or warm tap water around the bottle. Measure: the balloon’s circumference with a string. Cost: about $3. See Why do bike tires go soft in winter?
Does a bigger bottle make a better thermometer? Change: bottle size, same straw. Measure: how far the coloured water rises, in millimetres, from ice water to warm water. Cost: about $3. See How does a thermometer know?
Does mass disappear in a reaction? Change: open cup or capped plastic pop bottle. Measure: mass before and after on a kitchen scale. Use goggles, a 1.5 to 2 L fizzy-drink bottle only, an adult standing by, and no more than 1 level teaspoon of baking soda and 100 mL of vinegar. Cost: about $3. See Where does the mass go?
Which acid takes more baking soda to cancel out? Change: vinegar or lemon juice, same amount. Measure: quarter-teaspoons of baking soda until red cabbage juice turns from pink to purple. An adult makes the cabbage juice with hot water. Cost: about $5. See Can red cabbage tell acid from base?
Do more blades make a pinwheel spin faster? Change: number of blades (4, 6 or 8) on a paper pinwheel. Measure: turns in 30 seconds, blowing through a straw from 20 cm away. Cost: about $3. See Can the wind power our school?
Why is winter sunlight weaker? Change: the angle of a flashlight. Measure: how many grid squares the light covers at each angle. Cost: about $0. See Why don’t we use solar power everywhere?
Does salt change how fast water freezes? Change: 0, 1 or 2 teaspoons of salt in 250 mL (1 cup) of water. Measure: check every 30 minutes and record when each cup is frozen solid. Cost: about $0.
Does a heavier pendulum swing faster? Change: the number of washers on a string, same length. Measure: time for 10 swings. Most people expect heavier to be faster. The swing time barely changes, and explaining a “no difference” result is excellent science. Cost: about $3.

The fair-test planner

Students can copy this onto paper or into a notebook. Fill it in before touching any materials.

1. My question: Does ______ change ______?

2. My prediction: I think ______ because ______.

3. The one thing I will change: ______

4. The things I will keep the same: (list at least three)

5. What I will measure, and with what tool: I will measure ______ in ______ (units) using a ______.

6. How many trials: I will test each one ______ times. (At least 3. Five is better.)

7. My data table:

What I changed	Trial 1	Trial 2	Trial 3	Average
Version A
Version B
Version C

To find the average, add the trials and divide by how many there are. K–2 students can skip the average and circle the biggest number instead.

Writing the conclusion: claim, evidence, reasoning

A strong conclusion has three parts. Students can use these sentence starters.

Claim (the answer to the question)

I found that ______.
My prediction was correct / not correct because ______.

Evidence (the numbers that prove it)

In my test, ______ measured ______, but ______ measured ______.
The average for ______ was ______, which is ______ more than ______.
In ______ out of ______ trials, ______.

Reasoning (the science that explains it)

This happened because ______.
This matters because ______.
If I did this again, I would change ______ so that ______.

Younger children can say their claim aloud while an adult writes it down. “I found out the sock kept the ice the longest, because I saw it still there when the others were water” is a real conclusion.

A simple judging rubric

Teachers can use this as is or adjust it. It works for one judge with a clipboard and two minutes per project.

Looks for	Not yet	Getting there	Got it
Question	A topic, not a question	A question, but hard to test	A clear question that can be tested
Fair test	Several things changed at once	One thing changed, some others not kept the same	One thing changed, others kept the same and listed
Measurement	Described in words only	Measured once per version	Measured with units, repeated at least three times
Results	Data missing or unclear	Data in a table	Data in a table and a graph that’s easy to read
Conclusion	Restates the prediction	A claim with some evidence	Claim, evidence from the data, and a reason why
Explaining it	Can’t explain what they did	Explains the steps	Explains the steps, the result and one thing they’d change

For K–2, judge only the first three rows and the last one. Ask the child to show you what they did. That tells you more than the board.

For parents: help without doing it for them

You know the projects that were clearly built by a parent. Judges do too. Here’s how to help in ways that keep it your child’s work.

Ask questions instead of giving answers. “What do you think will happen?” “How will you know?” “Is that test fair?”
Handle the unsafe parts. You run the hot tap, use the knife and plug in the fan. Your child does the measuring, counting and recording.
Let the handwriting be theirs. Wobbly letters and crooked graphs are fine. For young children, write down their words, not yours.
Let it go wrong. If the plants die or the results don’t match the prediction, that’s not a failed project. It’s a result. Ask, “Why do you think that happened?”
Don’t fix the board. Help with glue and scissors if they need it, but let them choose what goes where.

A six-week timeline

Six weeks out: pick a question. Check it’s testable and that you can get the materials. If it involves growing plants, start this week.

Five weeks out: fill in the fair-test planner. Gather materials. Do one practice run to check the test works.

Four weeks out: run the real trials. Record everything in the data table, including the odd results.

Three weeks out: finish any missing trials. Work out averages and draw a graph.

Two weeks out: write the conclusion using the claim-evidence-reasoning frame. Take or draw pictures of the setup.

One week out: build the board: question, prediction, materials, steps, data, graph, conclusion. Practise explaining the project out loud in two minutes.

The day before: pack the board, any small pieces of equipment that are safe to bring, and the notebook. Get a good sleep.

Fair day: stand beside your project, smile, and tell the judge what you wanted to find out. You know more about this question than anyone in the room.

If you’d like a fuller version of any linked idea, every Fieldbook lesson comes with a teacher guide and a student sheet. Browse the library by grade, or print the free Science Fair Planner with every page above ready to fill in.