1. searching for an exact phrase 

ex.  "game theory" 
If game theory is not typed inside quotation marks, the results will include all documents with the word game and the word theory, not necessarily the phrase, game theory. 
2. using AND to add more specialized terms to your search

ex. spirals and Archimedes instead of spirals
The results of this search will include both the word spirals and the name Archimedes.  If the word AND is omitted, some search engine results will have either spirals or Archimedes but not necessarily both. 
3. eliminating very common words from your search (and, in, the)

The Math Forum, www.mathforum.org
This fabulous site that is maintained by Drexel University.  It caters to kids of all ages, parents and teachers.  You can "search for math" from their home page and/or check their frequently asked questions.  No need to include MATH as part of your search since all links are math-related. To make sure that the resources you find are more on your level, you might search at the middle school level more specifically, mathforum.org/students/middle/midsearch.html.  If you get really stuck after trying a number of things, you can e-mail one of the "Dr. Math's."

Yahooligans, www.yahooligans.com
There may not be as much math information at yahooligans, the yahoo web guide for kids, but consider doing a search in two ways: 

1. search all of yahooligans for your topic
2. search the math section only

Sample search in yahooligans: Math and Sports had 6 results, not all relevant.
Same search in math section of yahooligans:  only 1 result.

• try to eliminate personal websites such as geocities as they may not be as reliable as other sources
• be more specific in your search words and/or consider doing an advanced search