Geogebra

GeoGebra is a simple,powerful and open source tool that helps every student to understand maths concepts, to solve problems and to get the easy solutions.

This is a tool that can be used for plotting a graph in statistics, explaining probability, geometry, or trigonometry and algebra.

You can create your constructions with points, vectors, segments, lines, conic sections.The interface is very minimalistic and this helps everyone to create interactive web pages with more features.