"Graphs and charts are great because they communicate information visually. For this reason, graphs are often used in newspapers, magazines and businesses around the world."
There is a free trial version of the materials in the National Library of virtual manipulatives. Math topics Numbers and Operations, Algebra, Geometry, Measurement and Data Analysis & Probablity are covered. I did not come across anything asking for money so I a not certain there is a cost. There are tons of manipulatives to access from each of the above categories. This site is associated with the Uta State University.
Mathematics is a live science with new discoveries being made every day. The frontier of mathematics is an exciting place, where mathematicians experiment and play with creative and imaginative ideas. Many of these ideas are accessible to young children. Others (infinity is a good example) are ideas that have already piqued many children's curiosity, but their profound mathematical importance is not widely known or understood. The MegaMath project is intended to bring unusual and important mathematical ideas to elementary school classrooms so that young people and their teachers can think about them together.
Site all about math. It provides resources for teacher, parents and students. The site includes math games, math lessons, math practice, math dictionary and I also used a graphing function from this site.
Shape It Up is one of many good educational games and activities on Kinetic City. Shape It Up is an activity that would be good for use in an elementary school Earth Science lesson. The activity presents students with "before" and "after" images of a piece of Earth. Students then have to select the force nature and the span of time it took to create the "after" picture. If students choose incorrectly, Shape It Up will tell the student and they can choose again.
Decimal Squares provides simple games for students to use to develop their math skills. The games do not require an account to play and they work on any web browser that has current Flash plug-ins installed. The games are best suited to middle school students, but could be used with upper elementary grades or with high school freshmen.
Sheppard Software has a fantastic collection of free web-based educational games. Sheppard Software's free games cover Science, Math, Social Studies, and Language Arts. Most of the games are appropriate for elementary and middle school students, but some games are appropriate for high school students. The geography games are particularly good.
Novel Games provides a large list of fun, simple, educational games. The list of games includes numerous math and word games. All of the games are free and are available in multiple formats. All of the games on Novel Games are easily embedded into your class blog or website.
Learning Games for Kids offers games for mathematics as well as many other content areas. Most of the games on Learning Games for Kids can be played directly on the website although some do link out to other sources.
Super Text Twist is a simple word game similar to Word Twist which asks plays to identify words from a set of jumbled letters. The Super Text Twist game be played online or downloaded for use offline.