I'm looking for good math resources for my 6 year old. He wants his own "real math book" to read this summer. He likes to see the big picture without a lot of repetition. For example, when I showed him how to add columns of numbers he immediately got the fact that the rules for carrying work the same way for 6 digit numbers as they do for 2 digit numbers. He gets frustrated with books that present the same concept over and over. Right now he's interested in multiplying and fractions. Does anyone know of any good resources?