GoalSay that materials can be mixed and heated to make something new, and that some changes cannot be undone.
New words
mixture · two or more materials mixed togetherbake · to cook food in an ovennew material · something different from the things you started with
Explanation
We can mix materials together. When we mix flour, eggs, milk and butter we make a runny mixture called batter. A grown-up can put the batter in a hot oven. We say it bakes. After baking, the batter has changed into a solid cake. A cake is a new material. We cannot turn it back into batter. An egg changes in the same way. A raw egg is a runny liquid. When an adult cooks it in a pan, it turns solid and cannot go back. This is different from ice and chocolate. They can melt and freeze again. Only a grown-up uses the oven or the cooker.
Worked examples
Nodira stirs squash into water in a jar. The two liquids mix and make a drink. She can see a mixture, but it is still a liquid.
Dad cracks an egg into a pan and cooks it. The runny egg turns into a solid. It cannot become runny again.
Bread dough is soft. After an adult bakes it in the oven, the bread is firm and has a crust. Baking made a new material.
Class activity
Make dough (with an adult): mix two cups of flour, half a cup of salt and a little water in a bowl. Add a spoon of oil. Stir with a spoon, then squeeze with your hands until it is a soft dough. Look at it: is it a solid or a liquid? What was it like before you mixed it? An adult can bake a small piece of dough in a warm oven. Let it cool. How has it changed? Do not eat the dough, and wash your hands.
Practice
1
Name two things that Aisha could mix to make a drink.
For example: squash and water, or milk and a little cocoa.
2
Which of these has been baked?
B, the bread.
3
Can a baked cake turn back into runny batter? Why?
No. Baking made a new material, and this change cannot be undone.
4
Who should use the oven when we bake: a child alone, or a grown-up?
