For parents who are looking for appropriate math training materials, in addition to the books I absolutely recommend (see my post in the FinanceHubs forum), there is another great book for the middle school level (or advanced elementary school level) kids. Here is the description of the book:
The IMLEM Plus edition of Hard Math is designed for students participating in both the Intermediate Math League of Eastern Massachusetts and Mathcounts. The topics align with modern middle school curricula: fractions, decimals, percents, prime factorization, plane and spatial geometry, probability, statistics, combinatorics, algebra, modular arithmetic, etc. But Hard Math challenges students to develop a deeper understanding: it asks much harder questions than standard texts and teaches the material and problem solving strategies students need to attack them. For example, rather than asking students to write 2/5 as a decimal, it might ask students to use the fact that 99999 = 9 × 41 × 271 to find the tenth digit in the decimal expansion for 1/271.
The organization of the book is designed to serve IMLEM students' needs: the first five chapters cover exactly what students should learn for each of IMLEM's monthly contests. But the text can also serve students preparing for other math contests or as general enrichment.
The author Glenn Ellison is the Gregory K. Palm Professor of Economics at MIT and a parent volunteer at Bigelow Middle School. He didn't have the opportunity to participate in math contests in junior high, but was a member of the Harvard math team which won the national championship on the 1985 Putnam exam.
Amazon has the book for only $12, with excellent reader reviews. Check it out.