Teaching objective: 1. Further explore the calculation method of irregular object volume and experience the fun of exploration. 2, will correctly solve some simple practical problems. Understand the mathematical thought of transformation from it. 3. Cultivate students' migration ability, inquiry ability and innovative thinking ability. Teaching aid preparation: 1. Cuboid container, measuring cup, water, sand, plasticine and syringe. 2, apples, table tennis, eggs, drinks, winter dates, napkins and other irregular objects. Teaching process: 1. Import 1. We have studied the volume calculation and volume calculation of cuboids and cubes, so how to calculate cuboids and cubes? (Answer) 2. What is volume and unit of volume? What's their connection? 3. Cuboid cubes are regular objects, which can all be calculated by calculation formulas. However, the volume of many objects cannot be calculated by formulas, such as table tennis, eggs, drinks, winter dates, napkins and so on. So how do you calculate the volume of these irregular objects? We will study this problem again in this class. (Writing on the blackboard) 2. Explore communication and solve problems 1. The students saw an apple in the teacher's hand. What shape is it? I want you to find a way to measure its volume. (Blackboard: Irregular Object) Can it be measured directly? Think of a good way to measure its volume. Clear operation process of collective communication: 2. Demonstration, with observation records of teachers and students. Third, expansion and extension: just now we measured the volume of apples. Teacher, there are some irregular objects here. Can you think of more ways to measure its volume? The teacher prepared table tennis, eggs, drinks, winter dates, napkins and other irregular items for everyone. Please select the items to be measured and the tools you need, send a representative to the front to collect them, and then cooperate with the measurement. Fourthly, the experimental results are introduced: through cooperation, all groups have found the measurement method. Next, we ask each group to send representatives to report to the class. Other groups can evaluate the group's methods, such as: whether the method is applicable, whether it is innovative, the size of the error and so on. Five, try the hand 1. Observe the picture below to solve the problem. If you put three big balls and six small balls in the first tank, how much water will be discharged? The volume of an apple is about 245 cubic centimeters, and the volume of a packing box is 7.35 cubic decimeters. How many apples do you think this box can hold? Sixth, review and improve. What did you gain from this class?