(A) create a situation, ask questions

1. Teachers use multimedia to display teaching situation maps and guide students to observe.

Teacher: Students, do you know the benefits of afforestation to human beings? Our school plants trees every year. Let's take a look at the math problems in tree planting today.

Please observe the picture carefully and tell your deskmate what you see. How many bundles of young trees are there? How many trees are there in each bundle? ) What math questions would you ask?

Guide the students to ask "How many trees are there in a small tree?" .

(2) Solve problems and explore oral calculation methods.

1. Answer independently.

Students list the formula of 20×3 and try to calculate it.

2. Group communication.

Ask the students to talk about the meaning of their listed formulas in the group, and then talk about the calculation method.

3. Communicate with the whole class.

The representative of the group made a speech and came to the conclusion that 20 in 20× 3 = 60 represents 20 trees in each bundle, 3 represents 3 bundles, and 60 represents a * * * with 60 trees. Students may propose the following calculation methods:

(1)20×3 is the sum of three twenties: 20+20+20 = 60;

(2) Because 2× 3 = 6 and 20× 3 = 60;

(3) 20 can be regarded as 10×2, so 20×3 can be changed into 10×6.

As long as students' calculation methods are correct, teachers should encourage and praise students and let them choose their favorite methods to calculate.