Chemistry teacher Jack Forrest carries out a number of quick and simple experiments with his year 7's to reinforce the idea that mass is always conserved. First, students mix colourless solutions of potassium iodide and lead nitrate together, to form a bright yellow mixture, clearly showing a chemical reaction has taken place. They weigh the solutions before and after mixing and observe that mass remains the same. Jack then demonstrates a classic Carbonate reaction, reacting marble chips and hydrochloric acid. Knowing mass is conserved; the group discuss why the mass decreases in this reaction. Finally, he finishes of by cooking popcorn kernels, which increase in volume when boiled, but the mass stays the same. Jack, a chemistry teacher at Stocksbridge High School finds these short, snappy experiments work well with lower age groups.

Video Series: Great Lesson Ideas
Release Date 2010