Can someone me understand ratios? like equivalent ratios? i don't remember learning that when i was in school. it's so i can explain it to my 11 year old son for his homework.

Equal ratios are those that are equal to each other. 

Example:-

4/2 = 8/4

Also, ratios compare to values, and there are 3 ways to write a ratio. 

4/2 and 4:2 and 4 to 2

You can write endless equivalent ratios. How? What you do in the numerator, you do in the denominator.

For example:

5/4, if we multiply for 2:

5/4 = 10/8

or 3:

5/4 = 15/12

or to divide for 5:

1/0,8

Good look with your son.