Hello scientists! In the past your school has helped me solve many a problem. Now I have a new one for you! Could you could get your heads together and explore this

next topic for me too?

Have a look and see what you think…

St James’ School Science Challenge

October 2013

Hmm…what’s this

one about?

How many of you have wobbly teeth?

Lots of children in school have wobbly teeth, making it difficult to eat their

apples at snack time!

We have thought about cutting the apples into bitesize pieces for

you…

But by the time you come to eat them, they’ve turned brown!

Some things to think about…

• HOW to investigate the problem? What could you do?

• What will you look at? Covering the apple, putting it in something etc

• What equipment will you need?• How will you do your investigation?• What do you think will happen? What

is your prediction and WHY?

Calling all scientists!Can you investigate what

we can do to stop the apples turning brown

once we have cut them?

Can you report your findings to us here at

the Science Institute so that we can tell other

schools?

Good Luck!

Some things to think about…

• Why does an apple go brown when it is cut?• What stops it turning brown before it is cut?• Will you still want to eat the apple

afterwards?• How are you going to show/tell other people

what you have found out?• What do you think will happen?

• Why do cut apples turn brown?

The brown colour is because your apple has rusted! That's because apples are rich in iron, which is present in all their cells. When you cut an apple, the knife damages the cells. Oxygen from the air reacts with the iron in the apple cells. This is just like rust that forms on the surface of iron objects. An enzyme helps make this reaction go faster.

• If you cut a browned apple into two again, you'll notice that the insides are still white. That's because the cells inside were intact, and did not let oxygen enter right inside.

• Lots of other fruits and vegetables also turn brown when cut. These include bananas, pears and even potatoes.

• There's no harm in eating an apple that has turned brown, for the iron oxide will not affect you. But when you're making a fruit salad or apple pie, the browning may make it look unattractive. Here are some things you can do to stop or slow the browning:

• Cut and keep the apples under water. This prevents air from reaching the iron. But it may cause some vitamins to leach into the water.

• Rub the cut apples with lemon juice. The acid in the lemon juice stops the polyphenol oxidase from working.

• If you're making apple pie, you can dip the apples in boiling water for a few seconds and take them out. This is called blanching, and it stops the browning enzyme.

• You can add some salt to the apples; the salt stops the enzyme. Do this if you don't mind the salt-and-sweet taste that will result.

• Keep the apple pieces in an airtight jar, or wrap them in cling wrap very tightly. This also stops air from getting to them.

• And finally, the method we like the most. Turn your apple into apple juice. The iron oxide gives it the special golden-brown colour, and it's a tastier way to consume an apple!

Year R and 1 learningLevel 1• I can talk about what I can see.• I can share my findings in different ways – verbal, pictures etc• I can say how things have changedLevel 2• With support, I can think of how we could answer a question/find

something out• I can use simple equipment with support• I can say how things are similar & different• I can make comparisons between objects/events• I can suggest why something has happened based on something I

already know (personal experience etc)

Year 2(3c)

• I can suggest factors to investigate• I can decide what evidence to collect • With some support I can carry out a fair

test• I can talk about why a test is fair• I can find out more using books and

computers • I am starting to make choices about how I

present what I have found out.• I can explain what I did to others and why.