# Geometry

### Yarn or Line Designs

Making line designs is an excellent extended project for a 4th or 5th grade class.  It integrates many skills and concepts, and students get to take something home they can display.  A class can complete a line design, starting only with the center of a large circle on an 11” square of paper.

### The Rhombus Machine

The Rhombus Machine (and The Parallelogram Machine)  are meant to illustrate why rhombi, rectangles, and squares  are also parallelograms.  I have an activity entitled Quadrilateral Sorting, or How can a square be a Rectangle?  that uses several models of these devices.  As you can see, this machine makes only rhombi.  How does that work?

### Angles and Circles

When we first introduce angles, we can immediately draw the connection between angles and circles.  This is a rich and interesting relationship, and because we are drawing circles and angles, and measuring them numerically at the same time, we can clearly see the relationship between the numbers and the drawings.