Teaching preschool children about addition and subtraction should be fun and hands on, as opposed to just memorizing math facts such as 1 + 1 = 2 or 4 - 1 = 3.
Although flash cards are being advertised as a popular trend, even in infancy, using flash cards to help young children memorize math and other facts is not appropriate for young children because the concepts don't have any real meaning to them. Young children get more out of counting in real life situations.
Using the terms add, subtract, take away, etc. can help children further understand that you are adding/subtracting. For example, you can have children help you set the table by telling them, "There will be 7 people for dinner. Can you put 7 plates on the table?" Then if Sally can't make it to dinner, you can say, "Sally won't be joining us for dinner. Can you take her plate away? Now how many people will be joining us for dinner?" Another example would be taking the children to the grocery store and asking them, "Can you add 3 cans of soup to our cart?" or "I only need 3 apples. How many are in this bag? If we have 4 apples, is this more or less than 3? How many do we have to take away to have 3?" When children experience math in this way, they learn the concepts and their value.
Watch this eXtension Alliance for Better Child Care video for another example of how you can teach addition and subtraction to young children:
To learn more about teaching math skills in child care, take a look at the following eXtension Alliance for Better Child Care articles: