This is a classic investigation into the effect of different liquids on your teeth. If you can’t get easy to access to some teeth (ask your local tooth-fairy) – then an eggshell can provide a simple stand-in. Clean (cooked & boiled) chicken bones can also work well.

You will need

• Egg shells (boiled or sterilised) to model our teeth
• Different liquids to test – for example water, vinegar, cola, orange juice, milk
• Plastic cups or beakers
• Sticky labels or marker pens
• (optional, replace the eggs with cooked chicken bones which have been boiled and scrubbed)

How to do it

• Prior to the session, prepare the egg shells. Dispose of the white and yolk and boil the shells in water for at least 5 minutes.
• 1/3 fill each of the cups with the different liquids and label them.
• Place an egg shell into each of the cups and press it under the surface so it fills and sinks.
• Leave it for 24 hours then carefully pour away the liquids and add fresh liquid to each cup.
• Leave for a week, observing the eggshells every day. Freshen up the liquid if necessary.

What’s going on?

The drinks that have the biggest affect on the shells contain acids – juice, vinegar and cola are all very acidic. Egg shells (and teeth) contain calcium carbonate. This reacts with the acid to form carbon dioxide and a soluble form of calcium. This means that the hard shell of the egg (and teeth) dissolves, leaving only softer parts.

This video I filmed for Twig Education shows you what to do:

Bouncy Egg

You can supersize this experiment by creating a bouncy egg by soaking a raw egg in vinegar for at least three days.

• Take a raw egg and carefully place it into a glass or jar
• Fill the glass with white vinegar until the egg is completely submerged
• Leave the egg in the glass for 2 or 3 days. Check the egg each day. When the egg has started to become translucent you will know it is ready.
• Remove the egg from the glass and rinse it in tap water. Whilst rinsing gently rub the outside of the egg and the white film will come off leaving you will a translucent egg.
• Examine the egg. You’ll notice that is feels rubbery (like a bouncy ball). Then lift the egg 10cm or so in the air, let go and watch it bounce.

What’s happening?

As for the egg shell experiment the vinegar begins to dissolve the shell. Eventually, the shell will completely dissolve leaving just the thin membrane of the egg. The result is an egg that looks and feels like a bouncy ball.