Word problems are my exception to the not buying math curriculum rule. I do usually buy a book of word problems for the grade appropriate for the child. Evan-Moor makes a nice book with one word problem a day for about $17. I think word problems are so essential. Students may be skilled at additon and yet not understand in what situation that skill may be applied. They may have the technical ability to solve problems when the numbers are provided but be lost when asked to extract the same numbers from words. For their daily word problems, I sometimes ask if they can prove them, even if they get them right, so that I can see what method they use to get their answers.
source: Mathematics; a Way of Thinking, Bob Baratta-Lorton