1. Review 1+3= 4 7+3= 10 2+3= 5 7+4= 11 7+5= 12 3+3= 6 7+6= 13 3+3+3= 914
7+7=
7+7+7= 21 14

3. 1 4 4

4. 2 4s
4+4 =8

5. =12
3 4s
4+4+4

6.
=16
4 4s

8. 6 4s

9. 3 5s
5+5+5

10. 4 6s

11. 6 0s

12. √ Who is right? This picture shows 4 3s. This picture shows 3 4s.
4+4+4

13. √ × × Right or wrong? (1)3 groups of 8 （ ） (2) 2 groups of 5。 （ ）
(3) = （ ） ×

14. How to do the calculation?
6 10s =
5 6s =

16. Conclusion
6 4s = 24 8 12 16 20