Throwing youngsters into the deep end doesn't teach them how to swim. But once they've learned the basics, those who practice their strokes can become better swimmers. The same is true for math. Here are several pre-K-12 Web sites with math resources for both teachers and students.

- National Council of Teachers of Mathematics (NCTM): Principles & Standards for School Mathematics

At this site you can learn more about the principles underlying high-quality mathematics instruction. NCTM's publication, Principles and Standards for School Mathematics, offers guidelines for math education in many categories. - Math Ideas

Looking for a tried and true way of supporting math instruction in your K-6 class? Visit this Web site for dozens of math instruction ideas by teachers for teachers. Activities teach angles, place value, graphing, weather tracking, prime factors, and more. - 321 Know Math

Featuring dozens of activities, this resource for teaching division offers interactive practice with division facts, divisibility, dividing fractions and decimals, and division problems. - Word Problems for Kids

Can't get enough practice with word problems? At this Canadian Web site for students in grades 5-12, you'll find dozens of word problems (with problem-solving hints and answers) organized by grade level. - Math Problems with a Point

Selected by the NCTM as an exemplary Web site, this math-oriented resource focuses on problem solving. Targeting students in grades 6-12, it provides practice with a variety of problem types. Users can search for resources by math topic (For example, discrete mathematics, topology, calculus); time required, problem-solving strategies; technology (such as calculators, graphing calculators, and spreadsheets); or keyword. - Online Logic Puzzles/Games: Battleship

The popular strategy board game makes its way to the computer screen as a solitaire Flash applet. A Macromedia Flash Player and Shockwave plug ins are required. Download them for free at www.macromedia.com/downloads. - Welcome to Maths Is Fun

Started by a British math teacher who wanted to encourage an interest in mathematics, this site now hosts a variety of multiage, basic math activities for instruction, review, and fun. Children can practice math facts, solve puzzles, learn how to calculate the area of several shapes, and print worksheets and math tables for offline review.