Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.
Use rolled up offcuts of card, sections of drinking straw, or split pins and staples to fix the two sections together.
One piece represents the forearm and hand, and the other represents the upper arm and shoulder blade, together with the main muscles which move the arm - the biceps and the triceps.
To make the arm bend, pinch in one of the "muscle" sections to make them shorten.
Of course, your own arm is somewhat better than this!
In the space below, list as many ways as possible in which your (whole) arm is more advanced than this model.
> wrist rotates
> arm rotates at shoulder
> fingers move