I spent time in a middle school science class this week and they were studying chemistry. The teacher had set up the class the day with some background knowledge and an experiment. She burned a magnesium strip to create magnesium oxide.
On my watch, the students were to do some reading in their text then build a model of the chemical equation with mini-marshmallows and toothpicks. It was to be a discovery session as they figured out how to represent the equation with the marshmallows. At first the kids struggled some, but they soon figured out what they could do and the day was a success. After creating the model they sketched their model in their science notebooks.
At that point, some of the marshmallows were eaten!