Cells are the micro building blocks of all living organisms, and though there are many different kinds allowing us to have many different functions, we will focus on the basic ones associated with animals, plants and bacteria.
I would start by drawing out annotated diagrams of all 3 kinds of cell and annotating them, and discussing the features labelled and their function- ie the vacuole of a plant cell for support of the plant, the nucleus for storing genetic information etc.
We would then try again with a blank sheet of paper drawing the structures, unassisted this time and discuss the outcome.
At the end of the session we would revisit the structure and function of all 3 cells to check the lesson sunk in!