I remember my mom struggling to teach me pre-algebra ahead of the school curriculum. My uncle (a math teacher) mailed us a bunch of "part-is-to-whole-as-part-is-to-whole" word problems of increasing complexity and various forms, and working through those made a lot of things click. The concreteness helped, and it also made me understand the equivalence between proportions, fractions, decimals, percents, and their real-world concepts, plus it has some simple solve-for-x attached to it. And it's learning-by-doing instead of learning-by-reading.