I really enjoy using Microsoft PowerPoint to create introductory math lessons. With PowerPoint, you can make lessons creative, colorful, interactive, and engaging for students. PowerPoints can be used with SMARTboard technology or something as simple as a laptop computer or mini notebook.
Here are two sample math lessons (via SlideShare) that I made recently using PowerPoint. Both presentations, which you can download for free for your own personal use from thatmathlady.com, are quite short and relatively simple to use.
Both presentations are uploaded in my Math Vocabulary binder on http://www.claco.com, too!