Full Screen Version
Click on 'Rods', to choose a Cuisenaire rod and then drag it onto the squared background. More rods can be added in a similar way and aligned as you wish. A rod can be rotated by $90^\circ$ by clicking any key whilst dragging. The background squares can be altered (for example increasing/decreasing their size) using the 'View' menu.

You could use this environment for all sorts of purposes - perhaps to explore addition and subtraction, factors and multiples or ideas about fractions.

For more ideas, look at the Notes section, or go to this page where there is a collection of Cuisenaire problems.