🌱 Does planting a seed deeper make it slower to come up?

My hypothesis

If I change how deep the bean is planted, then how many days until the shoot pokes out of the soil will ______, because ______.

🔊 You fill in the blanks. Think about the food packed inside a bean, and how far the shoot has to push on it before it reaches light. A guess is a good because: the test finds out.

Change, measure, keep the same

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 3 levels 3 times.

What you need

• 🫘 Dried beans from the grocery bag (pinto, lima or kidney): 9, all the same kind
• 🥤 Paper cups with a hole poked in the bottom: 9, the deeper the better
• 🪴 Potting soil
• 🚰 Water from the tap
• 🥄 Measuring spoons
• ✏️ A pencil
• 🩹 Masking tape, to mark lines
• 📏 A ruler

Steps

1. Soak nine beans in a cup of water overnight.🔊
2. Fill nine cups with soil to 2 cm below the rim, and label them 1, 3 and 6 cm, three of each.🔊
3. Mark 1, 3 and 6 cm up a pencil with masking tape, so you can measure each hole.🔊
4. Poke a hole to the right depth in each cup, drop in a bean, and cover it with soil.🔊
5. Give every cup a tablespoon of water, and set them all in a warm, bright spot.🔊
6. Every day, give each cup the same tablespoon of water.🔊
7. Check every day, and write down the day each shoot pokes through the soil.🔊
8. If a bean hasn't come up by day 14, write 'not up' beside it.🔊
9. Find the mean days for each depth and draw a line graph.🔊
10. Wash your hands after touching the soil.🔊

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

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 line graph, because the thing you change is a number that goes up.

Why it works

🔊 A bean carries a packed lunch, the food stored in its two halves, to feed the shoot until it reaches light. A deeper shoot has farther to push, so it usually takes longer to come up. Plant it too deep and the food can run out before the shoot gets there, which is why seed packets say how deep to plant.

Going further (7th and up): Change a second thing: plant at each depth in sand and in potting soil, and draw a line for each.

Board layout

This project at your grade

From 4th grade up, the table gets a mean column. See every project for 3rd grade, or print a blank results table.

What a judge will ask

• What did you change, and what did you measure? I changed how deep the bean is planted and measured how many days until the shoot pokes out of the soil, in days.
• What did you keep the same, and why does that matter? I kept the same kind of bean, soaked the same night and the same cups and soil the same, so the only difference was how deep the bean is planted.
• How many times did you test it? 3 times at each of my 3 levels.
• If you did it again, what would you change or test next? I'd plant at each depth in sand and in potting soil, and draw a line for each.

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

• 🫘 How much water do bean seeds need to sprout?2nd–6th grade · 10 days of testing · free🌦️ Growing and weather · 🌱 Outside and plants
• 🪣 Which soil lets water through fastest: sand, potting soil or garden soil?3rd–8th grade · 1 day of testing · about $1🌦️ Growing and weather · 🌱 Outside and plants