No matter what materials you choose, it is most important that you supervise your child constantly so that mistakes get caught rather than practiced. I learned this particular lesson the hard way. When my daughter was young, she did something that needed "attention." I no longer remember what it was that she did, but I told her to write the sentence "I will not disobey my parents again" 50 times. I should have known better, but I didn't check on her at the beginning and then I got busy. So, sometime later, she brought me 50 sentences of "I will not disobey my parents agen." She had just practiced misspelling "again" as "agen" __ 50 times! I'm not certain that we ever really got that fixed. This issue of NOT practicing mistakes is extremely important. Parents shouldn't give worksheets as busy work and teachers should only use them if you are going to have a non_math teacher substitute. White boards with supervision are always a better way to practice skills. If you need some time to do chores, your child will get much more benefit by helping you with the chores. And maybe you can work in a little discussion of numbers or counting while you do chores together.
Books _ Among the dozen or so math word_problem books of note published in the past decade, one, written by Mary Jane Sterling, from a well_known, popular brand of information books, which I'm unable to name here, stands out. The publisher has put a decent chunk of the book online at books.Google.com (go to books.google.com and search for sterling word problems). Striking Difference in Child Development _ If you are considering arranging extra math drills for your child, keep in mind that story problems are more like the real_life problems he or she will encounter, and, they help develop his or her critical_thinking skills. Children develop mental maturity like they do physical maturity. Think about the strikingly different mental development that ordinary math worksheets might foster in comparison to math word problems. Priorities _ Ordinary math worksheets certainly serve a purpose, but think carefully about the ratio of those to story problems when helping your child prioritize his or her available math study time.