Math practice · Week 11 · Thursday
I can check someone's work and explain a strategy.
Look: Lin says 38 + 45 = 73
- Check the ones: 8 + 5 = 13.
- 13 is 1 ten and 3 ones. Lin forgot the ten.
- Tens: 3 + 4 + 1 = 8. The right answer is 83.
Be the teacher. Is the work right? If not, fix it.
- Sam added 56 and 28 and got 74. He wrote 6 + 8 = 14. What did he forget?Answer: He forgot the ten from 14. The answer is 84.
- Bo did 72 − 45 like this: 72 − 50 = 22, then 22 − 5 = 17. Is he right?Answer: No. He took away 5 too many, so he must add 5 back: 22 + 5 = 27.
- A farmer has 47 hens and gets 36 more. Rosa did 40 + 30 = 70 and 7 + 6 = 13, so 83. Is she right? Which strategy?Answer: Yes, 83. She broke the numbers into tens and ones.
Teach a strategy.
- Solve 65 + 27 = ____ your way. Write how and why it works.Answer: 92. Answers vary. Look for: steps and a because sentence.
Second Grade · Week 11 · Thursday · secondgrade.com