Big idea: Composing and decomposing (putting numbers together and taking them apart) is the most important number idea before Grade 1. When a child knows that 7 is 5 and 2, or 3 less than 10, adding and subtracting become much easier.
Common difficulties:
- Not believing the total stays the same. After a shake-and-spill, children may want to count all over again. That's okay. Ask, "Did we add any? Take any away?"
- Finding the hidden part. This is hard at first. Use real objects and let them check under the bowl.
- Partners of 10. Start with 5, then 6 and 7, then 10. Ten frames and fingers help a lot.
How to help: Play shake and spill and hide-the-part games often. Turn an egg carton into a ten frame: a dozen carton has 12 cups, so tape over 2 cups at one end to leave two rows of 5. Say number pairs out loud: "You have 3 grapes and 2 grapes. That makes 5 grapes!"