Students practice their knowledge of factors and products. There are links to lessons on how you might use this engaging game in the classroom.
http://illuminations.nctm.org/ActivityDetail.aspx?ID=29

To play this one-person game well, students need to work with equivalent fractions, and be able to add and subtract fractions. Don't forget to turn the sound on!
http://illuminations.nctm.org/ActivityDetail.aspx?ID=18

Here is a neat two-person version of the game.
http://standards.nctm.org/document/eexamples/chap5/5.1/

And here is the above game without all of the instructions:
http://standards.nctm.org/document/eexamples/chap5/5.1/#applet

In this cooperative learning activity, students are presented with a real-world problem: Given a mirror and laser pointer, determine the position where one should stand so that a reflected light image will hit a designated target.

This investigation allows students to develop several rational functions that models three specific forms of a rational function. Students explore the relationship between the graph, the equation, and problem context. From NCTM Illuminations.
http://illuminations.nctm.org/LessonDetail.aspx?ID=L606

The factor game is a classic! Play against a friend or play against the computer. All you need to win is a good knowledge of factors and a bit of logic to figure out a winning stragegy!
http://illuminations.nctm.org/ActivityDetail.aspx?ID=12

This virtual manipulative allows you to solve simple linear equations through the use of a balance beam. Note: it is a large file, so it may take some time to load.
http://nlvm.usu.edu/en/nav/frames_asid_201_g_4_t_2.html?open=instruction...

Algebra Balance Scales - Negatives
This version includes negative numbers and negative coefficients on x.
http://nlvm.usu.edu/en/nav/frames_asid_324_g_4_t_2.html?open=instruction...

The presented problems ask you to change the time on the right clock. Click Check Answers to see if your answer is correct. Then, click New Problem for start a new problem.
http://nlvm.usu.edu/en/nav/frames_asid_318_g_3_t_4.html?open=instruction...

This probability game is an electronic version of the old TV game show Let's Make a Deal, hosted by Monty Hall. It has a surprising outcome!
http://nlvm.usu.edu/en/nav/frames_asid_117_g_3_t_2.html?open=instruction...

Explore the graphs of functions interactively.
http://nlvm.usu.edu/en/nav/frames_asid_109_g_3_t_1.html?open=activities&...

The Golden Rectangle is a plot created by starting with a rectangle, chopping off successive squares, and drawing quarter circles with a radius equal to the side of the square that was cut.
http://nlvm.usu.edu/en/nav/frames_asid_133_g_3_t_1.html?open=instruction...

This manipulative allows you to construct factor trees (to the prime factors) for two numbers, and then from the prime factorization, you are asked to identify the Least Common Multiple (LCM) and the Greatest Common Factor (GCF) of the two given numbers.
http://nlvm.usu.edu/en/nav/frames_asid_202_g_3_t_1.html?open=instruction...