Here are a couple of ideas that are very simple to produce, but make use of colours to create interesting lesson activities for any interactive whiteboard or screen. None of these use anything too complicated apart from shapes, text and the ability to change the background colour. They can be used in any software, including Smart Notebook, ActivInspire and PowerPoint.
Hidden Words
In this example we’re looking at what happens when you add a “y” to the end of each word. Each word is written in yellow and red, with the background set to red at the end to hide all the red words. A shape (in this example a magnifying glass, but it could just be a light coloured rectangle) is put on the back layer (“send to back”) so that as you move it about it reveals the letters.

Shapes
Several shapes have been drawn, and their lines and fills set to be the same colour as the background (again make this with a white background first to make things easier). A white shape has been “sent to back” which can be used to investigate.
Ask the pupils what they think the shape is from just the small piece of information they can see – look at the angle – what do they think it could be.. is it a square? etc etc.

Magic Paper
The sums on the left have their answers written in yellow so you cannot see them. Drag them over to the right and the answers are revealed. All students have “thinking time” to solve them, then can drag over to the other side to see if they are correct. Here’s how to do it.

If you’ve got any other great examples, let me know in the comments!
Using Colour Creatively in Interactive Presentations
The Whiteboard Blog – Education, Technology and Science CPD and Support