The goal of mathematics activities in the large class of the open courseware "Seven-person Composition";
1, by trying to operate the learning tool, let the children divide 7 into two parts, there are six ways to divide 7, and make records.
2. Through discussion and analysis, it is understood that a number is divided into two parts. If one part without Feng increases 1, the other part will decrease 1.
Activity preparation:
There are 42 plastic ducklings with learning tools.
Activity flow:
First, review the composition of 6
Playing the game of "touching the ball", several cards appeared. The teacher asked: What is this number? Answer "6" Teacher: There are six teachers and children playing touch games today. Teacher: How many balls did my 1 ball touch? A: Your 1 ball touched five balls.) The teacher asked, and the children can answer collectively, in groups or individually.
Second, the collective attempt activities
The image of the dog and rabbit's home appeared.
Teacher: How many ducklings did this puppy invite to their home today? (Children answer: 7) What should the rabbit do if it invites the duckling to be a guest? (Children's answer ...) Let the children take the seven ducklings on the table and divide them into two parts, one for the puppy and the other for the rabbit. (Children's operation) Let children divide the numbers differently from others. (First attempt)
The teacher asked the children to answer, how did you divide it? The children answered, the teacher operated the duckling to the home of the puppy rabbit, and listed the typing (). The children answered one, the teacher listed one and wrote six types of division.
Teacher: It is divided into two parts. * * * How many ways are there? A: * * * There are six kinds, and collective reading is divided into seven kinds.
Teacher: Just now, every child was divided into one category, but there were 6 out of 7. If you can do it again in six ways. The children operate the "plastic calculation duckling" and the teacher erases the split type on the blackboard. (Second attempt)
Teacher: Now I'll ask so-and-so Jiao Xiao to tell you how to divide it, the child replied. The teacher wrote down the formula of 7 to 7 on the blackboard, as shown in the figure. When the teacher asks the child to answer, he should pay attention to asking for representative opinions. First, there are repetitions, but there are actually no six. Second, although there are six kinds, they are not divided in order; The third is to distinguish six kinds in order. Please look at the children, who has the best method and who has the right method. Through discussion, the children made it clear that the method of sorting in order is good.
The teacher erased all the combinations on the blackboard and asked the children to write down six 7' s on the homework paper. (third attempt)
The teacher asked: 7 can be divided into 1 and 6.
The teacher asked: 7 can be divided into 2 and 5.
The teacher asked: 2 is 1, and the child answered: 2 is 1 more 1.
The teacher asked: 5 to 6, and the child answered: 5 is smaller than 6 1.
This makes it clear that seven can be divided into six orders, and finally it is concluded that seven is divided into two, where 1 is increased and 1 is decreased.