/sci/ - Science & Math

1. Why are most kids taught up to 12 times multiplications from memory in primary school? Why not 11 or 13?

2. When learning math, why aren't they taught to use letters for unknown values instead of the simple omissions of a number? (Example: My brothers homework features questions such as 1 + _ = 3, instead of 1 + x = 3).

3. Why aren't they taught very basic substitution? Rather than just filling in the blanks, teach them how to get the answer the way they will be doing with more complex problems in high school?