Science Fair

Grown-ups

Which kind of ball bounces highest?

1st–4th grade · 1 day of testing · about $3 · ages 6 to 10 · 40 minutes a sitting

  • 🧍 Drop from standing: never climb
What you need for the ball kinds and bounce project: four different balls: tennis, rubber, foam and ping-pong, a tape measure, or a long ruler, masking tape, to mark lines

My hypothesis

If I change the kind of ball, then how high the ball bounces will ______, because ______.

You fill in the blanks. Think about how much each ball squashes when it lands, and how quickly it springs back. A guess is a good because: the test finds out.

Change, measure, keep the same

CHANGE

the kind of ball: Tennis ball, Rubber ball, Foam ball, Ping-pong ball

MEASURE

how high the ball bounces, in cm

KEEP THE SAME

  • the same floor
  • dropping every ball from the same height
  • letting go, never throwing
  • measuring the bottom of the ball

Scientists call the thing you change the independent variable and the thing you measure the dependent variable. The things you keep the same are the controls: if one of them changed too, you wouldn't know which change made the difference. Try each of the 4 levels 3 times.

What you need

  • Four different balls: tennis, rubber, foam and ping-pong
  • A tape measure, or a long ruler
  • Masking tape, to mark lines

Steps

  1. Tape the tape measure up a wall, with 0 at the floor.
  2. Hold the tennis ball next to the tape, with its bottom at 100 cm.
  3. Let go. Don't throw it! Stand on the floor and never climb.
  4. A helper crouches by the tape and watches how high the ball's bottom gets on its first bounce.
  5. Write the height in your table under Try 1.
  6. Drop it two more times from the same spot.
  7. Do three drops with the rubber ball, three with the foam ball and three with the ping-pong ball.
  8. Find the middle number for each ball, and draw a bar graph.

Every step is one you can do yourself, with a grown-up nearby. Write each number down straight away, in the table below, so nothing is lost.

Your results table

MY RESULTSPeabody 🦉 peabody.kids/science-fair

Name ______________________ Fair day ____________

Question: Which kind of ball bounces highest?

I changed: Kind of ball   I measured: how high the ball bounces (cm)

Kind of ballTry 1 (cm)Try 2 (cm)Try 3 (cm)Mean
Tennis ball
Rubber ball
Foam ball
Ping-pong ball

MY GRAPH (a bar graph: kind of ball along the bottom, cm up the side)

What I noticed: ______________________________________________

From 4th grade, add the tries for each level and divide by how many there were: that's the mean, and it goes in the last column. Then draw a bar graph, one bar for each thing you tried.

📊 Make my graph🖨 Print the whole packet (9 pages)

Why it works

A ball bounces when it squashes against the floor and then springs back. A springy ball gives back most of its energy, so it goes up high. A ball that squashes and stays squashed, like foam, turns its energy into a little warmth and sound, so it bounces low.

Going further (7th and up): Change a second thing: drop each ball onto a hard floor and onto carpet, and draw a bar for every ball and floor.

Board layout

MY BOARD · 36 × 48 in tri-foldPeabody 🦉 peabody.kids/science-fair
  1. ❓ Question (10 × 8 in): Which kind of ball bounces highest?
  2. 💭 Hypothesis (10 × 9 in): If I change the kind of ball, then how high the ball bounces will ______, because ______.
  3. 🧺 Materials (10 × 12 in): 3 things: see your list.
  4. 🪜 Steps (22 × 9 in): 8 steps, three tries at each level.
  5. 📊 Results (22 × 16 in): Your table (Kind of ball down the side, tries across) and your bar graph.
  6. ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…

Materials to list: Four different balls: tennis, rubber, foam and ping-pong; A tape measure, or a long ruler; Masking tape, to mark lines.

Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.

This project at your grade

1st–3rd gradeTries: three at each level (one is fine at a first fair). The table: levels and tries, numbers or pictures. The graph: a picture, or a simple bar graph. The conclusion: what happened, in their words.
4th–6th gradeTries: three at each level. The table: units in the header and a mean column. The graph: a bar graph, or a line for a number that grows. The conclusion: right, partly or not, and the numbers that show it.

From 4th grade up, the table gets a mean column. See every project for 1st grade, or print a blank results table.

What a judge will ask

  • What did you change, and what did you measure? I changed the kind of ball and measured how high the ball bounces, in cm.
  • What did you keep the same, and why does that matter? I kept the same floor and dropping every ball from the same height the same, so the only difference was the kind of ball.
  • How many times did you test it? 3 times at each of my 4 levels.
  • If you did it again, what would you change or test next? I'd drop each ball onto a hard floor and onto carpet, and draw a bar for every ball and floor.

Make it yours

Keep this project on this device and Peabody counts down to your fair day, with a plan for each day. Nothing is sent anywhere.

Try next

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

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