On the move
26 September 2007Add to My Folder
Show children the purpose cams serve and then challenge them to construct their own cam-operated creation!
You have probably seen a cam in action without even realising it or knowing what it was. Can you recall a time when you’ve seen a small child pushing a toy lorry along the floor and while the lorry travelled along, the man in the driver’s seat bobbed up and down? Well, this is a cam doing just what it was designed to do! A cam is a type of mechanism consisting of a specially shaped piece of wood, metal or hard plastic, and its purpose is to create movement. Cams come in different shapes and sizes, depending on the movement required. In all cases, a follower sits on top of the cam and as the wheel is turned, the follower turns what is a rotary eccentric movement into a linear movement. Depending on the shape of the cam, the motion created can be simple or complex.
As an introduction to this part of the ‘Moving toys’ topic, allow the children to investigate models that contain cams. These could include different toys or models or construction kits (such as LEGO Technic) that contain cams as well as wheels with off-centre holes from which cams can be made. Set questions such as:
- Which parts rotate?
- Which parts reciprocate?
- How are the different parts assembled to allow for movement?
- How are the moving parts guided into place?
- What materials have been used?
- Why do you think those materials were selected to be used?
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