🍌 Does a paper bag make a banana ripen faster?

My hypothesis

If I change where the banana is kept, then how many brown spots the banana has on day four will ______, because ______.

🔊 You fill in the blanks. Think about what a banana might be giving off, and where it goes when the banana is inside a bag. 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

• 🍌 Bananas from the same bunch, still a little green: 9, all bought on the same day
• 🛍️ A paper lunch bag: 6
• 🍎 An apple: 3
• 🍽️ Small plates or saucers, all the same: 3
• 🩹 Masking tape, to mark lines
• 🖍️ Crayons or markers

Steps

1. Choose nine bananas that are all a little green.🔊
2. Put three bananas on the counter, each on a plate, away from the sun.🔊
3. Put three more bananas in three paper bags, one in each, and fold the tops over.🔊
4. Put the last three bananas in bags with an apple in each, and fold the tops over.🔊
5. Label every banana's plate or bag with masking tape, so you know which is which.🔊
6. Every day, take each banana out and count its brown spots bigger than a pencil dot.🔊
7. Write each count in your notebook, and put the banana back where it was.🔊
8. On day four, copy each banana's spot count into your table.🔊
9. Wash your hands, and do not eat the test bananas.🔊
10. Find the mean for each place, 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

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.

Why it works

🔊 Bananas give off a gas called ethylene, which tells fruit to ripen. On the open counter the gas drifts away, but a paper bag keeps it close to the banana. An apple gives off ethylene too, so a bag with an apple often ripens a banana even faster.

Going further (7th and up): Change a second thing: put one, two and three apples in the bag, and graph the spots on day four against the number of apples.

Board layout

This project at your grade

From 4th grade up, the table gets a mean column. See every project for 2nd grade, or print a blank results table.

What a judge will ask

• What did you change, and what did you measure? I changed where the banana is kept and measured how many brown spots the banana has on day four, in brown spots.
• What did you keep the same, and why does that matter? I kept bananas from the same bunch, all a little green and the same room, away from the sun the same, so the only difference was where the banana is kept.
• 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 put one, two and three apples in the bag, and graph the spots on day four against the number of apples.

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

• 🍎 What keeps a cut apple from going brown?2nd–6th grade · 1 day of testing · about $1🧪 Water, ice and mixing · 🧂 Kitchen things
• 🍞 Which bread turns the brownest in the toaster?4th–8th grade · 1 day of testing · about $3🧪 Water, ice and mixing · 🧂 Kitchen things