🥚 What softens an eggshell fastest?

My hypothesis

If I change the liquid the egg sits in, then how soft the shell feels after three days will ______, because ______.

🔊 You fill in the blanks. Think about what an eggshell is made of, and why bubbles might appear on it. 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

• 🥚 Eggs: 9 raw eggs, from the same box
• 🍶 White vinegar: about 3 cups
• 🍋 Lemon juice: about 3 cups
• 🚰 Water from the tap: about 3 cups
• 🥛 Clear plastic cups, all the same size: 9, big enough to hold an egg
• 🍽️ A baking tray or big plate
• 🥄 A spoon
• 🧻 Paper towels
• 🩹 Masking tape, to mark lines

Steps

1. Stand nine clear cups on a tray, and label three each water, lemon juice and vinegar.🔊
2. Use a spoon to lower one raw egg gently into each cup.🔊
3. Pour in water, lemon juice or vinegar until each egg is covered.🔊
4. Wash your hands after touching raw eggs, and never eat the eggs or drink the liquids.🔊
5. Make a scale on paper: 0 is a hard shell, and 5 is a rubbery egg with no hard shell left.🔊
6. Each day, look at the eggs and write down what you see, like bubbles or a rough shell.🔊
7. On day three, lift each egg out with a spoon onto a paper towel.🔊
8. Press each egg very gently with one finger, and give it a softness score from 0 to 5.🔊
9. Write each score in your table, throw the eggs away and wash your hands again.🔊
10. Find the mean score for each liquid, 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

🔊 An eggshell is made mostly of a rock-like stuff called calcium carbonate. Acids, like the ones in vinegar and lemon juice, react with it and make tiny bubbles of gas that slowly eat the hard shell away. Plain water does not react, and a thin skin under the shell keeps the egg together.

Going further (7th and up): Change a second thing: score the shells every day for a week, and draw a line for each liquid.

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 the liquid the egg sits in and measured how soft the shell feels after three days, in softness score, 0 to 5.
• What did you keep the same, and why does that matter? I kept eggs of the same size from the same box and enough liquid to cover every egg the same, so the only difference was the liquid the egg sits in.
• 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 score the shells every day for a week, and draw a line for each liquid.

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

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