It should involve all possible senses. Students read about a topic, hear about it, discuss it, write about it. Looking at a picture of a molecule is instructive but if you can hold a model of the molecule in your hands, touch it, feel it, rotate it in space, assemble and disassemble it, you gain a much more powerful and profound understanding. Repetition enhances retention. Contrary to the popular misconception that afflicts education today, there is nothing wrong with drill.
Drill is essential in transferring learning from short term to long term memory.
Drill is underutilized only because it is boring to the teacher. But it is not boring to the computer. Entertainment and education should be the same thing. The only instruction that is boring is bad instruction. There are no uninteresting topics, only uninspired teachers or uninterested students.