An excellent way to improve your understanding when reading an extended piece of text is to convert the key processes into a series of labelled diagrams or a graphic

Decaffeination provides an excellent context that can be used to add depth to a sequence of lessons on separation techniques. The Education in Chemistry article Time for a (decaf) cuppa illustrates how the different degrees of solubility of caffeine in various solvents is exploited in the selective removal of caffeine from two of our favourite drinks, whilst still maintaining their delicious taste and aroma.

In this DART (Directed Activity Related to Text) learners produce a graphic to illustrate a sequence of steps to separate caffeine from tea leaves and coffee beans. The process is initially modelled for extraction with organic solvents and supercritical CO2, before learners are required to draw their own graphic to illustrate how caffeine can be extracted from coffee simply with water.

The separation techniques that learners will encounter in this resource include dissolution, distillation and filtration.