Coffee Tin Crawler
Key Stage 2
• To demonstrate to children how energy can be stored and used for specific purposes. (While there is no specific mention of stored energy in the curriculum orders the use of elastic bands in this investigation allows children a scientific model to explore movement)
Link to the National Curriculum
Sc4 Physical Processes
(Key Stage 1)* Pupils should be taught to:
“find out how the shapes of solid objects made from some materials can be changed by squashing, bending, twisting and stretching.
Physical Processes (Key Stage 2) Pupils should be taught to:
“ compare how things move on different surfaces”
* While this is not the domain of Key Stage 1, the statement at least gives the context for further work to come at Key Stage 2
Clearly in the statement for Key Stage 2 children above, it relates to push or pull. This equally applies to twist as in the case of the elastic band. In this instance all forces come from push/pull originally e.g. twist, bend, scratch, bang, scrape et al…..
Further non statutory guidance for Key Stage 2 states:
*“Pupils might work scientifically by: comparing how different things move and grouping them; raising questions and carrying out tests to find out how far things move on different surfaces and gathering and recording data to find answers to questions”
• *Will extra twists of the band make the coffee tin crawler go further?
• *Is there a pattern created by the extra turns in terms of distance?
What you need
- Large coffee tins or similar,
- paper clips,
- wooden/plastic beads with hole through centre,
- selection of elastic bands(thicknesses and lengths)
- length of dowel rod(easily obtainable from Builders Merchants
- Metre sticks
What you do
• Watch the video clip ”Coffee tin Crawler on the website: www.practicalprimaryscience.co.uk
• Drill/punch small hole in the centre of the base of the coffee tin
• Bend a large paper clip to form a hook entering the base of the tin being held in place on the outside by a piece of sellotape
• Cut a slot in the side of the tin to make a viewing hole
• Drill/punch a small hole in the centre of the plastic lid of the tin to correspond to the hole in the base of the tin.
• Attach one end of the elastic band to the hook in the tin, then thread it through the lid and bead on the outside of the lid
• Finally place a length of dowel into the loop on the open end.
Group / Class Organisation
• The children should be split into groups of threes or fours depending on the availability of extra adult help, apparatus available and past experience of working in small practical group situations.
• Recording sheets should be made available for each child with the emphasis on accurate recording of results and the need for repeat readings
How it works
• When the dowel is rotated through one revolution (wound up) it can be seen through the slot in the coffee tin side that the elastic band is being twisted to give it a stored energy.
• If after a sufficient amount of twisting the coffee tin crawler is laid on its side on a level surface the elastic band will try to twist back to its normal unwound position.
• Because the trailing dowel rod is resting on the surface the impetus created by the wound up band will force the crawler along.
• Clearly the more the elastic band is twisted the more energy is stored. This would allow an investigation into forces and especially stored energy posing such questions as;
• Will extra twists of the band make the coffee tin crawler go further?
• Is there a pattern created by the extra turns in terms of distance?
This investigation could form part of a wider project on Transport and lends itself well to a history topic with the Development of Transport throughout the Ages.
Follow up work
• Further investigations could relate to friction and how this affects travel with exciting additional activities related to the coffee tin crawler