As teachers and learners we are all familiar with situations in which we recognise that we know something, but do not really understand that information enough to know how to explain it or use it in other situations. For example, science students often rote learn the defi nition of osmosis and, despite being able to recite it word for word, struggle to explain how osmosis is different from diffusion or why osmosis is an important function in living organisms. More so, when challenged by different examples of the movement of substances across a membrane, despite knowing the definition, for many choosing that which is and is not an example of osmosis proves to be very difficult. When it comes to explaining the concept of osmosis in relation to the real world, having the definition alone is not enough. This problem of students learning school science but not genuinely understanding the concepts is an ongoing challenge for science teachers.