Teach Engineering
Solving Energy Problems
Here's your chance to save the world. The eighth lesson in a 25-part Energy Systems and Solutions unit has young scientists come up with ideas for individual or group projects. They identify ways to solve the energy crisis. Hope they...
Illustrative Mathematics
Similar Triangles
Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...
Noyce Foundation
Lyle's Triangles
Try five problems on triangles. Levels A and B focus on shapes that can be created from right triangles. Level C touches upon the relationship between the area of a six-pointed star and the area of each triangle of which it is composed....
Noyce Foundation
Fractured Numbers
Don't use use a fraction of the resource — use it all! Scholars attempt a set of five problem-of-the-month challenges on fractions. Levels A and B focus on creating fractions and equivalent fractions, while Levels C, D, and E touch on...
Illustrative Mathematics
Right Triangles Inscribed in Circles I
One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles and...
University of Cambridge
University of Cambridge: Nrich: Adding Plus
On this one page website sharpen your logic and addition skills while working on this challenge. The solution is available to double check your solution.