Teaching content: page 2 14- 15, unit 1, third grade primary school mathematics, People's Education Press, Example 3 and Example 4.
First, review old knowledge, review methods
1, oral calculation
53+26=
85-45=
67+ 19=
72-36=
2, column vertical calculation
245+ 16=
2、34- 16=
After the students finish their exercise books, they will revise them collectively, and then ask the students to talk about the calculation method (courseware display).
Second, create situations and ask questions.
1. The courseware shows the China Pavilion and other buildings in the Expo Park, guides students to look at the illustrations and introduces the mascot Haibao. Another example: many people come to the souvenir shop of the Expo Park to buy Haibao. What information did you get from the question and what questions can you ask?
Students answer, the courseware shows:
(1) How many "Haibao" did you sell on Monday morning and afternoon?
(2) How much more "Haibao" was sold in the afternoon than in the morning?
(3) How many "Haibao" did you sell in the morning than in the afternoon?
2. Reveal the topic: Today we will solve these problems together.
Third, explore independently and master the algorithm.
Teaching example 3 (1), learn the written calculation method of carry addition.
1, independent query. What do you want to know most? Students choose the question "How much sea to sell in the morning and afternoon?" Let the students solve independently, calculate vertically, and communicate in groups after completion.
2. The whole class reports and exchanges. Can you tell me what you should pay attention to when calculating by hand? Student: When adding with a pen, the same number should be opposite. Starting from single digits, whoever reaches ten will advance to the previous one.
4. Summary: The courseware shows how to add hundreds and dozens of strokes. A. alignment with the same number; B. start from the unit; C.if ten people pass ten, they get one hundred.
5. Q: A, why do ten people write 3 vertically?
B, why not 8%? (Answer: 3+5=8 in the hundredth place, plus 1 in the tenth place, so it is 9).