Where did the holes come from?

Do you like to make bread?  Does your mom make bread? Sometimes, when you look at a piece of bread, does it have holes in it?  Where did they come from? Does it mean you did something wrong?  NO!
    The holes in bread are caused by a chemical reaction ( واکنش شیمیایی ). We have learned in our kitchen chemistry that there are 2 kinds of changes:
1) physical changes ( تغییرات فیزیکی )
2) chemical reactions ( واکنش شیمیایی )
    When there is a physical change something changes form. For example, you can cut an apple into small pieces or you can turn water into ice.
    When there is a chemical change or reaction, the result is something completely new. For example, when a banana spoils ( یک موز فاسد می شود ) it is black and soft. It is no longer a banana. It is a new substance ( ماده جدید ).
    When you make dough ( خمیر ) you are really making a chemical reaction! When the yeast ( مخمر ) is mixed ( درآمیختن ) with water and sugar it makes carbon dioxide gas ( گاز دی اکسید کربن ). When the gas expands ( گسترش دادن ), it "pops" and make a hole. And you thought you were just making bread!

If you want your bread to taste REALLY good, fill the holes with jam!