Lesson plan "How are the numbers not enough"
Teaching objectives
1. Let students understand that both positive and negative numbers are generated from actual needs;
2. Make students understand the concepts of positive and negative numbers and judge whether a number is positive or negative;
3. Initially, positive numbers and negative numbers will be used to represent quantities with opposite meanings;
4. Cultivate students' ability of observation, induction and generalization in the process of forming the concept of negative numbers.
Teaching emphases and difficulties
The meaning of negative numbers.
Classroom teaching process design
First, ask questions from students' original cognitive structure
As we all know, mathematics is inseparable from numbers. This is the study of numbers. Now let's recall what types of numbers we learned in primary school.
After the students answered, the teacher pointed out that the numbers learned in primary schools can be divided into three categories: natural numbers (positive integers), fractions and zeros (fractions contain decimals), all of which are due to practical needs.
To represent a person's two hands, we use the integer 1, 2,
4.87、
To mean "no one" and "no sheep", we use 0.
But in real life, there are still many quantities that cannot be expressed by the above natural numbers, zeros or fractions or decimals.