The design of exercises should follow the development order from easy to difficult, from simple to complex, from basic to variant, from low to advanced, so that students at different levels can have a happy and pleasant experience of success after studying hard and make their learning more active. For example, in the third grade of primary school mathematics, the order of multiplication is oral calculation-estimation-pen calculation. It embodies the thinking law from easy to difficult and from low to high. So in teaching, I designed these topics: (1) The number of trains to be opened is 40×20, 60×20, 400×70, 12×30, 44×20,11× 400 (. 54×13, 33× 31,1× 25, 23× 34, 39× 27, 43×12,17× 28 In order to take care of students at different levels, students at different levels have the opportunity to experience success and maintain their enthusiasm for learning. I designed the expansion exercise when I was teaching multiplication formula: 1. Yu Ying primary school football team has 22 players, and the school took out 1500 yuan to prepare a football for each player. How much is 69 yuan short of each football? There are two kinds of sportswear in the sporting goods store, the big one and the small one. A big 32 yuan and a small 29 yuan. If you buy 38 sets of big sportswear and 55 sets of small sportswear.

(1) How much do you pay for these two kinds of sportswear?

(2) How much does a * * * cost?

The value of mathematics comes from our life, which allows students to understand mathematical knowledge in real situations and shows them a more intuitive, vivid and vivid stroke. Through practice, not only the comprehensiveness of students' thinking is cultivated, but also their innovative spirit is cultivated, so that students can be improved to varying degrees and everyone can gain something.