# Knock Off Numbers for Mental Math Practice! Activity

3.5 based on 44 ratings
Updated on Aug 15, 2013

If you counted the number of times in a day you use mental math, the answer would probably shock you! To your child, math may seem easier when he’s able to do the work on paper rather than in his head. If he only knew how much these mental math strategies will help in the future! This activity is a great starting point because it is quick, easy and involves only simple addition facts. Starting with mental math basics will give your child the confidence to take on longer, more complex problems. He’ll want to continue “knocking off” the math in his head – because he can!

• 1 die
• paper
• pencil

### What You Do:

1. With your child, do a quick “warm-up” review of addition facts to 10. Use flashcards or just quickly write out some facts on paper.
2. Give your child the die. Ask her to roll it 10 times. Each time she rolls the die, write down the number she rolls. You will end up with a vertical list of 10 numbers.
3. Next, explain to your third-grader that she will be learning a way to add the 10 numbers quickly and without writing anything! Help her find 2 numbers in the list that add to 10, such as 4 and 6. Model for her what to do. Say, “4 +6 = 10” and cross out the 4 and 6 while you say it. Then look for 2 more numbers in the list that add to 10, such as 5 and 5, and repeat the process. Once you’ve added all pairs that add to 10, add 3 digits to get 10. Say, “2 + 5 = 7, 7 + 3 = 10” and cross out the numbers you used. Explain that now you’re up to 20 and add the remaining numbers to get a total.
4. Continue practicing mental math with your third-grader. Have her roll the die as you record the numbers, then watch as she crosses out the numbers and “talks” her way through adding the list.  Make it fun and competitive by timing how long she takes to add the list mentally. After you time her, challenge her to “beat her time” on the next list. A small reward for beating her time is always a good incentive, too!
Brigid Del Carmen has a Master's Degree in Special Education with endorsements in Learning Disabilities and Behavior Disorders/Emotional Impairments. Over the past eight years, she has taught Language Arts, Reading and Math in her middle school special education classroom.
set

#### See in set:

Math Games for 3rd Graders