According to the active and curious psychological characteristics of primary school students, relevant hands-on activities are carefully organized in class so that all students can do them, thus stimulating students' potential motivation and interest in mathematics activities.
Case sharing: When I was teaching "symmetry axis" in the second grade of primary school mathematics, I first divided the students in this class into eight groups, and then distributed the prepared graphic pieces of paper (rectangle, square, isosceles triangle and circle) to each group, so that the students could discuss with each other first: guess how many symmetry axes each group has. Give me another discount and see if you guessed right. The winner is the group with the highest correct rate of the answers found within the specified time. Through fierce competition: guess, fold and have a look, the final result is: a rectangle has two symmetry axes, a square has four symmetry axes, an isosceles triangle has two symmetry axes, and a circle has countless symmetry axes. At this time, I asked the students: Is the parallelogram an axisymmetric figure?
The students replied in unison: Yes. However, after stopping for a minute, several students changed their minds and said, it seems not. I asked them why, and they shook their heads again, meaning not sure, just guessing. Just when I was wondering, one of my classmates stood up and said confidently, teacher, I don't think so. Because I just cut a parallelogram below, first fold it in half, then fold it diagonally, and the results can't overlap. The other students seemed to be inspired. Before I could say anything, they began to work. Through drawing, cutting and folding, it is finally agreed that parallelogram is not an axisymmetric figure.
Just as I was about to write the conclusion on the blackboard, a female classmate couldn't wait to shout: Teacher, I have different opinions. The parallelogram I cut is an axisymmetric figure. If you don't believe me, please pass me her work. Facts speak louder than words, so I showed this student's work to other students. They all stare big eyes and feel that everything in front of them is impossible, because they have just verified it below. At this time, I will let them think about why the same parallelogram has different conclusions. Through group cooperation and hands-on operation, the students finally come to the conclusion that if all four sides of a parallelogram are equal, then it is an axisymmetric figure, which naturally makes the students know the special parallelogram-rhombus, and also verifies that the rhombus is an axisymmetric figure. After class, the students spontaneously cut out many different plane figures, and easily judged which are axisymmetric figures, and summarized their characteristics.
In this lesson, I use hands-on operation to let students complete the teaching goal of this lesson in the competition: it is easier to master how many symmetry axes there are in a rectangle, a square, an isosceles triangle, a diamond and a circle. This is a colorful activity process full of observation, practice, thinking, imagination and communication, and it is also a challenging and interesting activity process. In the hands-on operation, students gradually feel that the original mathematics is not obscure and boring, but also endless happiness and fun.
Teaching based on graphics and geometry, through hands-on operation, not only cultivates students' innovative ability, but also deepens their memory of new knowledge; More importantly, it can let students know why and why.