Students often have trouble explaining biological process, especially when the parts are invisibly small.  Why do students get stuck with Osmosis, how can we use home made models to help them?

One way to get those quiet students who try to avoid answering questions or explaining anything in lessons is to help them (and oblige them to participate) using some kind of model.  This is best illustrated with an example.

Structure and finction of a kidney nephron

In this image a group of students have built a giant size model of a kidney nephron. They have listened to my explanation of the structure and function of the different parts of the kidnew nephron. The glomerulus, the proximal convoluted tubule and so on and now they have to construct a model of this using a beaker, a long rubber tube and a piece of polystyrene beading (80c each) from the local DIY shop.The four students with their backs to the board are each holding a specific structure and Rachel points at them one at a time and they have to explain the structure and function of their particular part of the nephron.  Once she has heared all the explanations Rachel has to try to tell the whole story. It's not expected that she will remember everything, but it's good to try. Then everyone moves along one place, Rachel takes hold of the glomerulus and we repeat the process. Each person now holds a different part of the nephron and has another part to explain. I often allow a little bit of helping, I call it cheating, but actually it's exactly what I want, the students are helping each other learn Biology! Once everyone in the group can explain the functions of all the structures the students are ready to answer a past paper question, annotate a diagram or comple a set of notes themselves. It's great fun and there is a lot of learning going on.  Another activity where I use bits from the DIY shop to build xymem vessels is here and I sometimes use sweets to expain membrane transport in a smaller, but similar way here.