Teaching content: (Beijing Normal University Edition) Unit 5 "What is a circumference" in the first volume of Grade Three Mathematics.
Teaching goal: to know the circumference by observing and operating specific things or figures. Can combine the specific situation, perceive the close connection between the perimeter and real life, and develop the preliminary concept of space.
Teaching emphasis and difficulty: understanding the meaning of perimeter.
Teaching preparation: multimedia courseware, cartoon pictures, watercolor pen, ruler, string, soft tape measure, study list and practice activity list.
Little ants draw the edges of leaves to reveal the concept of perimeter. Teacher: The students in our class are really observant and can point out the boundary lines on the surfaces of so many objects. Seeing the students' enthusiasm for learning, the little ant can't wait to try his hand. Look at the screen. (Courseware demonstrates ants crawling around the edge of leaves) Look and think: How do small ants draw?
Where does it start and where does it end? Student: Start from the starting point, draw along the sideline and go back to the starting point. Teacher: Little ants start from the starting point, draw along the edge of the leaves, and return to the starting point, that is, draw the leaves for a week. Teacher: We call the length of a week when a small ant crawls over a leaf the perimeter of the leaf. Teacher: Who can say what Zhou means?
Student: "week" means a week, and "length" means length. Teacher: What is the circumference of Xiong Tu? Student: The length of a bear picture is the circumference of a bear picture. Distinguish the concept of perimeter and deepen understanding. Summarize, popularize and assign homework. The teacher found that the children in our class are very observant and like to think. Through the study of this lesson, I know that the length of an object's surface and figure is its perimeter.
Do you know the circumference of the earth where we live? You can check the relevant information when you go home today, and we will continue to communicate in class tomorrow.