➰ Rubber band stretch: the whole packet

➰ Rubber band stretch · 5th–8th grade · 1 day of testing · free · 45 minutes a sitting

My days, if the fair is 14 days away

Count back from your fair day and write in each date. Fewer days than this? The jobs share days, in this order; nothing is skipped.

Dates from my teacher

• My question is due
• Testing starts
• My results table and graph are due
• My board is due

In this packet

1. 🗓️ My project plan
2. 💭 My hypothesis
3. 🧺 Change, measure, keep the same
4. 🪜 My steps
5. 📊 My results
6. 📓 My logbook
7. ✅ My conclusion
8. ✂️ Board titles to cut out
9. 🏅 The judge's questions and my certificate

If I change how many pennies hang on the band, then how far the rubber band stretches will ________________, because _____________________________________________

What I think will happen, in my own words:

4 levels × 3 tries at each = 12 tries in all. If anything you keep the same changes, you won't know which change made the difference.

What I need

• ➰ Rubber bands, all the same size: 2
• 🥤 A small paper cup with a string handle
• 🪙 Pennies: 40
• ✏️ A pencil
• 🩹 Tape
• 📏 A ruler

Be safe: 👶 Small parts

1. Tape a pencil to the edge of a table so it sticks out.
2. Loop the rubber band over the pencil and hang the empty cup from it.
3. Measure the band from the pencil to the cup's handle: that's your start length.
4. Put 10 pennies in the cup and measure again.
5. Take the pennies out, let the band rest a minute, and do it twice more.
6. Do three tries each with 20, 30 and 40 pennies.
7. Take away the start length to find how much it stretched each time.
8. Plot the points and see whether they make a straight line.

Write each number in your results table the moment you measure it.

I changed: Pennies in the cup   I measured: how far the rubber band stretches (cm)

MY GRAPH (a line graph: pennies in the cup along the bottom, cm up the side)

What I noticed: ______________________________________________

Write something every day you work on it, even the days you only gather things. More days? The three-page logbook prints from peabody.kids/science-fair/templates/logbook.

My hypothesis was ☐ right ☐ partly right ☐ not right.

I know because my numbers show:

What surprised me, or what might have gone wrong (7th and up):

Next time I would test:

Idea: Change a second thing: hang the same pennies from two bands side by side, and plot both lines on one graph.

1. What made you want to ask this question? Say something like: I wanted to know: how much does a rubber band stretch with each extra weight?
2. What did you think would happen, and why? Say something like: I thought changing how many pennies hang on the band would change how far the rubber band stretches, and I wrote down why.
3. What did you change, and what did you measure? Say something like: I changed how many pennies hang on the band (10 pennies, 20 pennies, 30 pennies, 40 pennies) and measured how far the rubber band stretches in cm.
4. What did you keep the same, and why does that matter? Say something like: I kept the same rubber band and the same cup the same, so only how many pennies hang on the band was different.
5. How many times did you test it? Say something like: 3 times at each of my 4 levels, and I found the middle number.
6. What did you find out? Show me in your numbers. Say something like: Look at my table: 10 pennies and 40 pennies gave different numbers, and here's the pattern.
7. Was your hypothesis right? How do you know? Say something like: My numbers show whether I was right, partly right or not, and I can show you where.
8. Did anything go wrong, or surprise you? Say something like: One try was odd, so I did it again and wrote it in my logbook.
9. If you did it again, what would you change or test next? Say something like: I'd change a second thing: hang the same pennies from two bands side by side, and plot both lines on one graph.