First, the teaching objectives

Knowledge and skills, understand the arithmetic of dividing decimal by integer, divide decimal by integer vertically, and calculate decimal division correctly. Process and method, in the process of exploring the calculation method of fractional division, feel the transformed thinking method, develop the preliminary ability of induction, reasoning and generalization, and further cultivate the estimation consciousness.

Emotion, attitude and values, feel the internal relationship between fractional division and integer division, feel the grandeur of solving practical problems in the Three Gorges Project, and inspire students' feelings of loving the motherland.

Second, the difficulties in teaching

Focus on teaching, know arithmetic, and can calculate correctly. Teaching difficulty, the determination of decimal point position in quotient. Introduce a PPT presentation of a new lesson: tourists visiting the Three Gorges. The contents of the information window show that the Three Gorges Dam was officially impounded on June 1 day, 2003. After three days of impoundment, the water level rose by 9.84 meters, the total length of the five-level lock of the Three Gorges was 6.4 kilometers, and it took 2.5 hours for the cruise ship to pass.

Let the students talk about what information can be seen from the picture, and then guide the students to ask a mathematical question according to the information in the picture: "On June 1 day, 2003, the Three Gorges Dam officially filled water, and the water level rose by 9.84 meters in three days": How many meters does the water level rise on average every day?

Guide students to think: how many kilometers should they run every week on average and how to arrange them? Students list the formula: 9.84÷3. Follow-up: After careful observation, what is the difference between this formula and the division learned before? Explore new knowledge. Question: Think about it, if it is a decimal, how to divide the dividends?

Estimate, Question: Let's estimate first. What is the approximate result of this formula? How do you estimate it? Students think independently, showing that 9.84 is 9, 9÷3 is 3 and the result is about 3. The problem of independent computing exploration algorithm: what is the exact result? Can you work it out? Give it a try. Students think independently first, write their own calculation process in exercise books, and then communicate with the students in the group.

Students demonstrate various algorithms.

9.84 m =984 cm, 984÷3=328 cm, 328 cm =3.28 m, so 9.84÷3=3.28. Fractional division can be converted into integer division to calculate: 984÷3=328, 9.84÷3=3.28. It can also be calculated vertically. Guide fractional division into integer division to calculate.