Horizons Mathematics 5, Book 1 (1998, Paperback)

This math program teaches from a spiral learning angle, in which specific skills are introduced and then re-introduced several times over the course of the year in a very systematic manner. My kids love Horizons Math because there are only a few problems of each type and anywhere from 5-10 different skills practiced in a single lesson. Not overly repetetive and very colorful workbook pages. Where in other math programs you might spend an entire chapter on double digit addition and then another chapter on double digit subraction, with Horizons you do many different kinds of problems every day. I feel this helps the kids to keep their skills sharp rather than just learning something and then moving on, never to see it again.