Thirty ml of sugar (sucrose) (C12H22O11) is mixed with 30 ml of sulfuric acid (H2SO4). A chemical reaction takes place to produce carbon, water (H2O) and sulfur trioxide (SO3). It's a fun chemical reaction to observe because there are dramatic changes in color, smell (make sure good ventilation is present), and temperature (so much heat is released that it melts the plastic cup). Gases are also produced which add to the drama.
I purchased Camtasia Studio over the summer and have used it to create tutorials for teachers that use our school's gradebook program. I just discovered a feature in the software that allows quizzes to be embedded in a video. I create Power Points all the time that are designed as mini tutorial/review sessions for my students. Camtasia has a plugin for Power Point that allows you to capture screen video and audio. So I decided to do a screencast for my isotope review/tutorial and then embed questions that students can answer to check their understanding. I'm very pleased with the results. I think I might do screencasts in the future for subs to run during an absence. It will be like I'm in the classroom, when I'm not.
This a favorite demo of mine that I have recently re-shot in HD. It's a dramatic demonstration of how the rapid condensation of water can create a vacuum.