This is an excellent introduction to the topic of simultaneous equations.

http://www.heymath.com/main/samples/us19/teacherstemplate.html

This web page does a great job of introducing the balance method to solve equations.

http://www.heymath.com/main/samples/us18/teacherstemplate.html

This is a fun little puzzle that is a bit trickier than it first appears.

http://www.mathplayground.com/hare_hounds.html

Compete against a friend, the computer or someone from around the world in a tug of war. To win, you have to compare the size of fractions quickly and accurately. Great fun! Note that the game can take quite a while if the competitors are evenly matched!

http://www.arcademicskillbuilders.com/games/dirt-bike-comparing-fraction...

An exciting way to practice creating equivalent fractions. You compete against your mates, the computer or other fraction-maniacs around the world to find equivalent fractions quickly and accurately.

http://arcademicskillbuilders.com/games/dirt-bike-proportions/dirt-bike-...

Ratio Stadium
Ratio Stadium is an additive arcade game in which the players have to find ratios that are equivalent to each other - and do it fast and accurately. Play against friends, against the computer or against other ratio addicts around the world. Addictive and great fun - three thumbs up!
http://arcademicskillbuilders.com/games/ratio-stadium/ratio-stadium.html

Ratio Blaster
Ratio Blaster is a one-person Space Invaders type game. How quickly can you blast the equivalent fractions out of the sky? Three thumbs up!
http://www.arcademicskillbuilders.com/games/ratio-blaster/ratio-blaster....

Compete against friends, against the computer or against players from other parts of the world in a variety of arcade games. To win, you have to answer addition, subtraction, multiplication or division questions quickly and accurately. You can set the range of numbers if you wish. Highly addictive and great fun! Three thumbs up!!

Jet Ski Addition
Can you answer the addition questions faster than your competitors? Only one way to find out!
http://arcademicskillbuilders.com/games/jetski/jetski.html

Island Chase Subtraction
A fun way to practice your subtraction facts.
http://www.arcademicskillbuilders.com/games/island_chase/island_chase.ht...

Multiplication Grand Prix
A car race with a difference. You power your car by answering multiplication questions as accurately and quickly as possible.
http://arcademicskillbuilders.com/games/grand_prix/grand_prix.html

Drag Race Division
The fastest and most accurate divider will win this race! Will it be you?
http://arcademicskillbuilders.com/games/drag_race/drag_race.html

More games can be found at
http://www.arcademicskillbuilders.com/

An interactive whiteboard resource to support any investigations using dominoes. In particular this resource was created to support classroom use of puzzles included in a book by Henry Ernest Dudeney in 1917. Books this old are in the public domain and so their contents can be distributed and built upon freely.

Instructions
http://www.teacherled.com/2008/06/24/dominos/

Resource
http://www.teacherled.com/resources/domino/dominoload.html

Printable Dominoes
http://www.teacherled.com/resources/domino/dominosheet1.pdf

Puzzle 1
http://www.teacherled.com/resources/domino/dominopuzzles1.pdf

Puzzle 2
http://www.teacherled.com/resources/domino/dominopuzzles2.pdf

Thirty particles fall from above. Use the repelling particle to nudge them into the correct box depending on whether they contain a square number or a prime number. This game is addictive - three thumbs up!

Instructions
http://www.teacherled.com/2008/09/02/particle-maths/

Resource
http://www.teacherled.com/resources/particle/particleload.html

This resource attempts to emulate a cell phone calculator. The teacher can demonstrate how to use the simple calculators to do useful real world maths. At the moment 2 types of real world questions can be generated by the resource: percentage discounts and area.

Instructions
http://www.teacherled.com/2009/01/03/cell-phone-maths/

Resource
http://www.teacherled.com/resources/cellphone/cellphoneload.html