Science
The 30-Day Bean Race
Four beans, four cups, and one thing you change on purpose. Measure every morning for thirty days, keep one cup untouched as the control, and find out what actually mattered.
Easy · 30 days, 5 minutes a day
Introduction
Most experiments you can finish in an afternoon are over before anything interesting happens. Plants do not work that way. A bean takes its time, and the waiting is what this project is really teaching.
You will start four cups on the same day, change exactly one thing between them, and then measure every single morning for a month. At the end you will have a chart that nobody handed you.
The Why
The cup where you change nothing is called the control, and it is the most important cup on the windowsill. Without it you cannot tell whether your beans grew because of what you did or because beans grow anyway. Changing only one thing at a time is what lets you claim the change caused the difference, and measuring on a schedule, including on the days when nothing appears to be happening, is what keeps you honest.
Step-by-Step Instructions
- 1
Soak all four beans in water overnight, so every one of them starts from the same point.
- 2
Set up four cups in exactly the same way: damp cotton balls or soil, one bean pressed against the side of the cup so you can watch it, and a label. Cup 1 is your control, and nothing about it changes for thirty days.
- 3
Pick one thing to change, and change it only in cups 2, 3, and 4. Amount of light, amount of water, or temperature all work well. Write down precisely what you changed and by how much.
- 4
Put all four cups in the same place at the same time, unless light or temperature is the very thing you are testing.
- 5
Every morning at roughly the same time, measure the height of each sprout in centimeters and take one photo of each cup from the same angle.
- 6
Write all four numbers on your sheet even on the days when nothing has changed. A row of zeros is real data, and skipping it hides how long germination actually took.
- 7
On day thirty, draw four lines on one chart, one per cup, with days along the bottom and height up the side. Then put your thirty photos in order and flip through them.
30-Day Growth Log
One row per day. Measure at roughly the same time every morning, and write a number down even when that number is zero.
| Day | Cup 1 (control) | Cup 2 | Cup 3 | Cup 4 | Notes |
|---|---|---|---|---|---|
| Row 1, Day | Row 1, Cup 1 (control) | Row 1, Cup 2 | Row 1, Cup 3 | Row 1, Cup 4 | Row 1, Notes |
| Row 2, Day | Row 2, Cup 1 (control) | Row 2, Cup 2 | Row 2, Cup 3 | Row 2, Cup 4 | Row 2, Notes |
| Row 3, Day | Row 3, Cup 1 (control) | Row 3, Cup 2 | Row 3, Cup 3 | Row 3, Cup 4 | Row 3, Notes |
| Row 4, Day | Row 4, Cup 1 (control) | Row 4, Cup 2 | Row 4, Cup 3 | Row 4, Cup 4 | Row 4, Notes |
| Row 5, Day | Row 5, Cup 1 (control) | Row 5, Cup 2 | Row 5, Cup 3 | Row 5, Cup 4 | Row 5, Notes |
| Row 6, Day | Row 6, Cup 1 (control) | Row 6, Cup 2 | Row 6, Cup 3 | Row 6, Cup 4 | Row 6, Notes |
| Row 7, Day | Row 7, Cup 1 (control) | Row 7, Cup 2 | Row 7, Cup 3 | Row 7, Cup 4 | Row 7, Notes |
| Row 8, Day | Row 8, Cup 1 (control) | Row 8, Cup 2 | Row 8, Cup 3 | Row 8, Cup 4 | Row 8, Notes |
| Row 9, Day | Row 9, Cup 1 (control) | Row 9, Cup 2 | Row 9, Cup 3 | Row 9, Cup 4 | Row 9, Notes |
| Row 10, Day | Row 10, Cup 1 (control) | Row 10, Cup 2 | Row 10, Cup 3 | Row 10, Cup 4 | Row 10, Notes |
| Row 11, Day | Row 11, Cup 1 (control) | Row 11, Cup 2 | Row 11, Cup 3 | Row 11, Cup 4 | Row 11, Notes |
| Row 12, Day | Row 12, Cup 1 (control) | Row 12, Cup 2 | Row 12, Cup 3 | Row 12, Cup 4 | Row 12, Notes |
| Row 13, Day | Row 13, Cup 1 (control) | Row 13, Cup 2 | Row 13, Cup 3 | Row 13, Cup 4 | Row 13, Notes |
| Row 14, Day | Row 14, Cup 1 (control) | Row 14, Cup 2 | Row 14, Cup 3 | Row 14, Cup 4 | Row 14, Notes |
| Row 15, Day | Row 15, Cup 1 (control) | Row 15, Cup 2 | Row 15, Cup 3 | Row 15, Cup 4 | Row 15, Notes |
Print two copies to cover all thirty days. Heights in centimeters. Use Notes for anything unusual: mold, a leaf opening, a cup you forgot to water.