Encourage your child to explain one strategy he can use to solve a problem. For example, “I know that 61 + 20 = 81 because 20 is two tens. I started with 61 and I counted on two tens: 61, 71, 81.”
Play “Make the Next Ten”: Partner A calls out a number (e.g., 28). Partner B tells how many ones are needed to make the next ten, and then says the number sentence (2; 28 + 2 = 30).
Play “Take out a Ten”: Partner A calls out a number (e.g., 67). Partner B takes out a ten, states the remaining part (57), and provides a related number sentence (67 - 10 = 57, or 57 + 10 = 67).
Play More/Less. For every number you say, ask your child to say the number that is 1 more, 1 less, 10 more, and 10 less.
At a separate time away from homework, practice sequences of math problems that use the same pattern, starting with a problem your child can easily solve. For example, you might use the sequence 9 + 3, 19 + 3, 29 + 3. Encourage your child to tell you what he noticed about the sequence of problems: “How did knowing 9 + 3 help with later problems?”
Practice basic addition and subtraction facts up to 20 with your child to help him build fluency. This fluency will help your child to solve two-digit addition problems. Challenge your child by putting the unknown number in different positions. For example, 8 + ___ = 12 OR ___ – 8 = 4.
To reinforce place value understanding, encourage your child to use place value language when adding. For example, to solve 23 + 54, instead of saying, “2 + 5 = 7 and 3 + 4 = 7,” she should say, “2 tens + 5 tens = 7 tens, and 3 ones + 4 ones = 7 ones.”
Practice subtraction facts up to 20, and encourage your child to use simplifying strategies for any facts that he has trouble recalling. For example, to solve 16 – 9, use the take from ten strategy: “I can break 16 into 10 and 6, and 10 – 9 = 1 and 1 + 6 = 7, so 16 – 9 = 7.”