Maths Challenge
Maths challenge.net: Lunes
A "three star" geometry problem where some experience of math problem solving skills and knowledge of circles is recommended to solve this lunes (parts of a circles) area problem
Maths Challenge
Maths challenge.net: Tri Angles
A geometry proof involving exterior angles of a triangle.
Maths Challenge
Maths challenge.net: Rectangular Circles
An area problem involving finding the area of a rectangle and a circle. The problem may be made into a general proof as well.
Maths Challenge
Maths challenge.net: Bag of Balls
A "three star" geometry problem which requires prior math problem solving skills and proof writing skills to solve this "Bag of Balls" radius of balls problem.
Maths Challenge
Maths challenge.net: Maximum Square
A challenging proof like geometry of finding the square inscribed in a triangle.
Science Education Resource Center at Carleton College
Serc: Pythagorean Theorem Investigations
In this activity, students will gain an understanding of the Pythagorean theorem and will recognize the variety of ways in which theorems can be proved algebraically, geometrically and visually.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Two Column Proofs
A response to an inquiry of how to prove a two column geometric proof problem at the Math Forum. This site gives a description of what a makes a proof and an example of a two column proof.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Building Two Column Proofs
Use this site to find details of how to construct a two column proof. Dr. Math responds to a question posed by a student and details the reasons for the order of steps and shows two different ways to do the same proof.
Maths Challenge
Maths challenge.net: Peculiar Perimeter
This is a "three star" geometry problem where prior math problem skills and proof experience is recommended. Tile constructions may be used to solve this perimeter and area problem.
National Council of Teachers of Mathematics
The Math Forum: Paper Folding Activity
This is a lesson plan of paper folding as a method of proof. A Java applet version of the activity can be accessed, giving the actual lengths and angle sizes.
Maths Challenge
Maths challenge.net: Coloured Strings
A "three star geometry problem" - requiring the knowledge of what a cuboid is and a some knowledge of how to do proofs.
Maths Challenge
Maths challenge.net: Leaning Ladders
Use your right triangle solving skills to solve this ladders in a hole problem.
Maths Challenge
Maths challenge.net: Sloping Square
A geometry problem of finding the area of a sloped square within a square.
Maths Challenge
Maths challenge.net: Semi Circle Lunes
A lune of a circle is defined and a problem of finding the area of two lunes is given.
Maths Challenge
Maths challenge.net: Glass in the Door
Use your knowledge of volume and weight to solve this posed problem of finding the weight of a glass in a door.
Maths Challenge
Maths challenge.net: Circular Pipes
A realistic world problem using the knowledge of chords and the parts of a circle to solve. Test your knowledge on this brain teaser!
Maths Challenge
Maths challenge.net: Tick Tock Triangle
This is a "three star" geometry problem where prior knowledge of probability is required to solve this "Tick Tock Triangle" problem, have fun!
Maths Challenge
Maths challenge.net: Shaded Triangle
A great geometry problem of area, encorperating many learned skills.
Maths Challenge
Maths challenge.net: Ice Cream Cone
Is summer close yet? Think about this yummy ice cream treat in a mathematical way! A problem of volume is posed for an ice cream cone.
Maths Challenge
Maths challenge.net: Triangle Area
Find the area of this triangle in a coordinate plane.
Maths Challenge
Maths challenge.net: Circumscribed Triangle
Find the area of this circumscribed triangle with your geometry skills.
Maths Challenge
Maths challenge.net: Measuring Mountains
Use your triangle solving skills to solve this triangle problem and then apply it to the real world.
Maths Challenge
Maths challenge.net: Chequered Floor
A problem involving patterns to find the solution to this sequence problem.
Maths Challenge
Maths challenge.net: Pentagon Star
An area problem using your knowledge about pentagons.