There are few subjects more difficult and complex than mathematics, and many children would rather avoid them. It begins simply enough with learning how to count up to ten, but the easiness of this subject seems to run away as soon as those numbers are part of everyday life. Part of the issue is that the numbers have little meaning when they are not use for any other purpose, but they can have important consequences when they are manipulated against other numbers.
The complexity of mathematics begins as soon as children start learning how to add and subtract numbers, and those who do not understand the basics will struggle throughout advanced courses. Some of them might never progress past the easiest levels, and it will tend to restrict them in higher categories of learning.