I'll show my son stuff that comes up much much later in math and if he can handle it, I'll let him do it.
I really strongly dislike (hate, abhor) the texts that have students write the answer to a division problem as the quotient with a remainder. It can cause problems later on (polynomial division).
It also is nasty because you learn addition, subtraction, and multiplication as operations where you do something with two numbers, you get a single number as answer, but all of a sudden, when dividing, you get two numbers as an answer, not just one. That's not true. You get one number as an answer - it just often isn't in the same set of numbers (rational instead of integer).
I do make my son use the remainder notation for a few problems, so he's exposed to it (especially due to standardized tests) but I prefer him to write answers as mixed numbers. Miquon does an excellent job of introducing division like this.