Top 10 things science fair judges ask

The questions are written in a child's words from the Alpine School District's judging procedures and Scientific American's five most common judge questions. Practise them with Peabody the judge.

How it's ordered: In the order a judge usually asks them: why, what you thought, what you did, what you found, what's next.

The ten, in order

What made you want to ask this question?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
What did you think would happen, and why?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
What did you change, and what did you measure?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
What did you keep the same, and why does that matter?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
How many times did you test it?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
What did you find out? Show me in your numbers.: Answer with your own project: name what you changed, what you measured, and point at your numbers.
Was your hypothesis right? How do you know?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
Did anything go wrong, or surprise you?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
If you did it again, what would you change or test next?: Answer with your own project: name what you changed, what you measured, and point at your numbers.
Can I see your logbook?: Dated lines from every day you worked show the project happened over time. Bring it.

Why judges ask each one, and a good answer at three grades

Each answer is about a real Peabody project, one for each age: dropping a ball from higher up (2nd grade), salt and a floating egg (5th grade) and a pendulum's string (8th grade). The numbers are examples; your answers use the numbers in your own table. Notice what grows with the grade: the older answers name the variables, use the mean and say how sure the numbers are.

1. What made you want to ask this question?

Why they ask: To hear that the project is yours. A judge can tell a question a child wondered about from one a grown-up picked.

2nd grade: “My ball bounces really high on the stairs, so I wanted to see if dropping it from higher makes it bounce higher.”
5th grade: “We read that people float more easily in the sea, and I wanted to test if salt really makes things float, with an egg.”
8th grade: “I saw a grandfather clock and wondered why its pendulum is so long. I wanted to find out what the length of the string does to the swing.”

2. What did you think would happen, and why?

Why they ask: To check there was a hypothesis before the test, with a reason. The reason matters more than whether it came true.

2nd grade: “I thought higher would bounce higher, because the ball is going faster when it hits the floor.”
5th grade: “If I add more salt, then the egg will sit higher in the water, because salty water is heavier than plain water and pushes up harder.”
8th grade: “If the string is longer, then it will swing fewer times in 15 seconds, because the weight has a longer path to travel each swing.”

3. What did you change, and what did you measure?

Why they ask: To hear the independent and dependent variables, even if the child doesn't use those words. One change and one measure is a fair test.

2nd grade: “I changed how high I dropped it: 25, 50, 75 and 100 cm. I measured how high it bounced, in cm.”
5th grade: “I changed how much salt was in the water, from 0 to 8 tablespoons. I measured how high the top of the egg sat, in cm.”
8th grade: “My independent variable was the string's length, 20, 40 and 60 cm. My dependent variable was the number of swings in 15 seconds.”

4. What did you keep the same, and why does that matter?

Why they ask: Controlled variables are what judges' rubrics reward most often, and the hardest part to fake: a child who kept things the same can say why.

2nd grade: “The same ball and the same floor, and I let go, I didn't throw it. If I threw it, it would bounce higher and that's not fair.”
5th grade: “The same egg, the same 2 cups of water, and stirring until the salt was gone. A different egg might be heavier and float differently.”
8th grade: “The same weight, letting go from the same distance out, and counting for the same 15 seconds. If the weight changed too, I couldn't tell which one made the difference.”

5. How many times did you test it?

Why they ask: One try can be a fluke. Repeating each level shows the child knows that, and from 4th grade the mean is expected.

2nd grade: “Three times at every height, and I wrote every one down.”
5th grade: “Three times at each amount of salt, and I worked out the mean for each one.”
8th grade: “Three trials at each length. My tries at 20 cm were 17, 16 and 17 swings, so the mean was 16.7, and they were close, so I trust it.”

6. What did you find out? Show me in your numbers.

Why they ask: To see the child read their own table and graph. Pointing at a number is the best answer there is.

2nd grade: “Look: from 25 cm it bounced 16 cm, and from 100 cm it bounced 64 cm. The higher I dropped it, the higher it bounced.”
5th grade: “At 0 and 2 tablespoons the egg stayed on the bottom. At 6 tablespoons it floated up, and at 8 it was nearly at the top. My graph goes up after 4.”
8th grade: “The means were 16.7 swings at 20 cm, 11.7 at 40 cm and 9.7 at 60 cm. Doubling the length didn't halve the swings, so it isn't a straight line: it curves.”

7. Was your hypothesis right? How do you know?

Why they ask: To hear the conclusion come from the numbers. A judge marks down "I was right" with no evidence, never an honest "I was wrong".

2nd grade: “Yes! Every time I dropped it higher, the bounce was higher. It's in my table.”
5th grade: “Partly. I thought any salt would lift the egg, but it didn't move until about 4 tablespoons. My numbers show it needs enough salt first.”
8th grade: “Yes for the direction: longer strings swung fewer times. But I'd guessed it would be twice as slow for twice the length, and the numbers show it isn't.”

8. Did anything go wrong, or surprise you?

Why they ask: Real science goes wrong. A judge wants to hear what the child noticed and what they did about it, and their logbook should agree.

2nd grade: “One time the ball hit my foot, so I didn't count it and dropped it again.”
5th grade: “The first time I didn't stir enough and the salt sat at the bottom. I stirred until it disappeared and did that try again.”
8th grade: “Counting swings by eye was hard, so I counted a swing each time it passed the middle going one way, and I had my sister count too.”

9. If you did it again, what would you change or test next?

Why they ask: A next question shows the child is thinking like a scientist, not finishing homework. It also shows they understood what they found.

2nd grade: “I'd try a different ball, like a tennis ball, to see if it bounces the same way.”
5th grade: “I'd try sugar instead of salt, to see if any heavy water makes it float or just salty water.”
8th grade: “I'd change the weight on the end and keep the length the same, to see if weight matters too. I don't think it will.”

10. Can I see your logbook?

Why they ask: The logbook proves the work happened over days, in order, with every try, not just the best ones.

2nd grade: “Here it is. Each day has the date and what I did.”
5th grade: “Here, with the day I set up, the three days I tested, and the day the salt didn't dissolve.”
8th grade: “Here it is: dated entries for each session, every trial's count, and the day I changed how I counted.”

Then practise out loud with Peabody as the judge, using your own project.

Sources: Alpine School District STEM Fair, judging procedures; Scientific American, the five most common questions from a science fair judge. Your school's sheet wins.

👨‍👩‍👧 For grown-ups and teachers: how much to help, the safety rules, and running a school fair. Science fair v0.16.1 · Checked 6 November 2026.