Dr.Math A valuable resource for frequently asked questions. Find the appropriate level or topic(middle School) and find a question similar to yours. http://mathforum.org/dr.math/
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
Triangle Inequality http://hotmath.com/util/hm_flash_movie.html?movie=/learning_activities/interactivities/triangleInequality.swf&return_to=Geometry%20Activities&title=Triangle%20Inequality