We all find ourselves in that position of having to explain maths to our younger children. In our house we have always used Lego® bricks to help with counting and fractions, it has helped both my son and now my daughter with their homework.
My brother, now an adult, can even remember as a kid learning fractions with Lego® bricks. They can be a fundamental building block of learning (pardon my pun). I found this handy pic to explain fractions. Happy Building!!