When two numbers are multiplied, the product is 1, then these two numbers are reciprocal numbers.

Note: don't mispronounce yourself;

2. For example:

Biruo said: 1/5×5= 1, then 1/5 and 5 are reciprocal; 0.4×2.5= 1, then 0.4 and 2.5 are reciprocal.

Note: For example, give a typical 1-2 group of fractions and integers; Decimals and integers, or 3-4 groups of decimals and decimals.

Suggestion: The most typical example.

25×4= 100;

125×8= 1000 (extended to 1)!

3. Analysis difficulty (error example)

The reciprocal of (1) only exists between two numbers. It cannot be said that as long as the product is equal to 1, it is reciprocal to each other. Example: Because 1/3× 12×2.5, the numbers 1/3, 12 and 2.5 are reciprocal;

Because they are equivalent, you can't just say one number. Example: 5 is the reciprocal, 0.3 is the reciprocal.

It should be said that 5 and 1/5 are reciprocal, or 5 is reciprocal of 1/5;

Step 4 focus on

The product between reciprocal must be 1, which is the reciprocal of other numbers! This is the essence of reciprocity!

The above is my opinion, you can arrange it according to the time, and you'd better ask a few students to answer your questions. For example, judge questions, multiple-choice questions, and calculation questions, and arrange them yourself!