Geometry Toolbox is a great geometry whiteboard resource has a virtual ruler, pencil, compass, and protractor. In the website you can choose among various colors to draw the lines or write explanations. You can create instant illustrations of geometry concepts, from simple measurement to constructions using angles and circles. I can use this tool in the classroom in many ways. I can use this on an interactive whiteboard or projector for students to see. I can use it in groups of students to practice measuring lines and angles. You can use the tool to teach students how to read a ruler. This tool can be very useful in the classroom.