Second, the teaching objectives

1? Combined with the specific life situation, feel and understand the mass units of kilograms and grams, and understand the actual mass of 1 kilogram and 1 gram.

2? Master 1 kg = 1000 g, and make simple conversion.

3? Experience the connection between mathematics and real life, and feel that mathematics is around.

Third, class records.

Preparation of teaching AIDS: balance, scale, milk, soybeans, paper clips, peanuts, military chess, 2 cents coins, apples, eggs, etc. Teaching courseware.

(A) create a situation to perceive the seriousness

1? Teacher: Students, two students did very well last class. The teacher should give them a warm hug.

The teacher picked up a particularly thin student at once, but couldn't pick up a fat student.

Comment on the introduction of "light" and "heavy" in Nature. )

Teacher: Just now, the teacher hugged these two students. What did you find?

Health: ××× light, ×××× heavy.

Teacher: Really? (Let a student try to hug again)

2? The teacher asked the students to take two items from the table and weigh them, saying who is lighter and who is heavier.

(Comment) The game of "hugging, hugging and weighing" naturally leads to the difference between objects, which stimulates students' desire to learn to weigh objects and creates a good situation for later exploration and study. )

(2) Explore new knowledge

1? Report the information collected before the exchange class.

Teacher: Just now, we can roughly compare the weight of two items by hugging and weighing, so what should we do if we want to know the weight of the items?

(Comment on the experience of awakening students' lives about quality. )

Health 1: Look at the net content marked on the package.

Health 2: Weigh it with a scale.

Teacher: Both methods are good! If the package of an item is marked with quality, we can know the quality of some items. Yesterday, the teacher arranged for students to go to the store to choose five kinds of foods they like to eat and investigate their net content. Who will report it?

Health report: 1 sausage contains 500g, and one sausage contains 45g, 60g and 75g. ...

1 potato chips 250g, 1 biscuits 500g, 1 "small dumbbell" bread 1kg. ...

Teacher: The materials collected by students are very good! The grams and kilograms mentioned by the students just now are international unified quality units, which are used to express the quality of goods. Today, we will know grams and kilograms! (The teacher writes on the blackboard on the topic "grams and kilograms")

(Comment) Combining with students' life experience, introduce the light and heavy weight units: kilograms and grams, so that students can realize the connection between mathematics and life. )