Screencasting is the single biggest "game changer" in educational technology today. Imagine not writing substitute plans and simply saying "play this video". You can talk to your students and show them the assignment yourself. Imagine that struggling student at home studying and he or she can hear YOUR voice and YOUR words explaining difficult concepts. Imagine that different way of learning math as explained by YOU to students and parents. Screencast o magic is a free tool that allows you to do all of this.