Activity intention:

The purpose of this activity is to let children understand the relationship between the weights of objects and learn to calculate the weight of objects by conversion. Because of the first contact with the mathematical content of transformation, considering the limited experience level of children, we chose a small number of "watermelon, pineapple, apple" teaching AIDS. In the use of school tools, children's activity materials are basically the same as teachers' teaching AIDS, so it is not recommended to use them. Although the "building block" teaching aid is difficult, it is beneficial to improve children's thinking.

Activity objectives:

1, understand the relationship between the weight of the object.

2. Learn how to calculate the weight of an object by conversion.

Activity preparation:

1, sheep, cats and chickens; A set of pictures of animals and a set of pictures of fruits.

2, printed with large, medium and small blocks of children's operation diagram a hand.

3. Children's activity materials, Volume III, page 27, one for each person.

Activity flow:

First, picture demonstration to understand the relationship between the weights of objects.

1. The teacher showed pictures of sheep, cats and chickens. Let the children compare who is lighter and who is heavier than them.

2. Let children line up according to their weight (from heavy to light, from light to heavy).

3. Demonstrate animal pictures and learn how to use the conversion method.

(1) teacher will figure 1:

One sheep equals three cats.

Question: How much does a sheep as many as a cat weigh?

(2) Show Figure 2:

A cat is equal to three chickens.

Question: How much does a cat as many as chickens weigh?

(3) Show Figure 3:

A sheep is equal to?

Question: So a sheep is as heavy as several chickens? (According to the child's answer, put 9 chickens at the other end of the scale.

4. Demonstrate fruit pictures and continue to learn how to use the conversion method.

(1) Show three pictures directly:

Let the children observe and discuss.

Teacher: Please observe it first, and then tell me that a watermelon is as heavy as several pineapples.

(2) Show the fourth picture:

How about two pineapples?

Secondly, combined with work activities, the calculation of object weight by conversion method is preliminarily explored.

1, the first operational exploration activity.

(1) Teachers demonstrate teaching materials and introduce the relationship between them:

A big block is as big as two middle blocks, and a middle block is as big as three small blocks. Think about how many small blocks a big building block should be as big as?

(2) Request:

Please try it on, put it on and stick it on.

(3) Children play with materials:

Discharge 1 large building block =6 small building blocks have an equivalent relationship on the working paper.

(4) Individual children introduce the operation process.

2. The second action exploration activity.

(1) Teachers demonstrate building block teaching AIDS:

A building block is as big as two medium-sized building blocks, and a medium-sized building block is as big as four triangular building blocks. Think about how many fast triangular building blocks there are in a building block.

(2) Children's operation data:

Discharge 1 large building block = equivalence relation of 8 triangular building blocks.

Third, plan and consolidate the experience learned.

1. Show the activity materials on page 27 of Book 3, and guide the children to complete the operation materials according to the instructions on the drawing page.

2. Strengthen individual guidance.

3. Comment activities.