1. Teaching content: Book II of Mathematics for Grade Five in Primary School published by People's Education Press. Unit II: Factors and Multiplies. The page number of the textbook is 12- 14.

Second, teaching suggestions:

After students have mastered the knowledge of factors and multiples, they can give the numbers of 6 1-2 in time and write their factors, so that students can know that the sum of the factors of 6 is exactly equal to 6 and try to find them. You can find several such numbers (you can kill two birds with one stone by practicing writing in a competition), so as to introduce the perfect number, introduce the knowledge of the perfect number and broaden your knowledge.

nature

1, all perfect numbers are triangular numbers. For example: 6 =1+2+3; 28= 1+2+3+...+6+7; 496= 1+2+3+...+30+3 1; 8 128= 1+2+3…+ 126+ 127。

2. The reciprocal of all perfect numbers is a harmonic number. For example:11+1/2+1/3+1/6 = 2; 1/ 1+ 1/2+ 1/4+ 1/7+ 1/ 14+ 1/28=2; 1/ 1+ 1/2+ 1/4+ 1/8+ 1/ 16+ 1/3 1+ 1/62+ 1/ 124+ 1/248+ 1/496=2。

3. It can be expressed as the sum of continuous odd cubes. All perfect numbers except 6 can be expressed as the sum of continuous odd cubes and increase regularly. For example: 28= 1? +3^3; 496= 1^3+3^3+5^3+7^3; 8 128= 1^3+3^3+5^3+……+ 15^3; 33550336= 1^3+3^3+5^3+……+ 125^3+ 127^3。

4, can be expressed as the sum of some continuous positive integer powers of 2. Not only that, their numbers are all continuous prime numbers. For example: 6 = 21+2 2; 28=2^2+2^3+2^4; 496=2^4+2^5+2^6+2^7+2^8; 8 128=2^6+2^7+2^8+2^9+2^ 10+2^ 1 1+2^ 12; 33550336=2^ 12+2^ 13+……+2^24。