The Flame Test Lesson.

It's one of those lessons that make pupils feel that STEM is fun! The flame test, because who doesn't like coloured flames? Just be careful not to overdo it with the Bunsen burner... whoops! The colour of the flame reveals the presence of metal ions in a compound. The thermal energy of the flame excites the electrons in the metal, which then fall back to the lower energy levels, emitting the excess energy as light. The colours show the different frequencies of light; they depend on the energy gap bridged by the electrons. The teacher's flame (red) is due to the presence of strontium, whereas the girl's (green) is caused by copper. The boy has clearly overdone it (while the Headteacher peeks through the door, bad timing), but it is probably calcium (orange flame). Here are the chemical engineers of the future in action!

Total number of parts, including minifigs, is 556.