It is more appropriate to add and subtract the first-order formula with the number less than 20. It can quickly improve children's oral expression ability, and it is a math game that children love to see and hear. Specific practices:

(1) Let the children count to 1.2, add odd numbers and subtract even numbers.

(2) The 1 odd number gives the addition. For example: 3+4=? (3) The second child who reported the even number said that he had to count seven solitaires and said a subtraction. For example: 7-5=? . Wait, solitaire.