Time: 30 minutes plus decorating time
20cm x 20cm piece of cardboard
Two 5cm lengths of drinking straw
String (natural fibers work best)
Colored pens, pencils, crayons or paints
1 On your piece of cardboard draw the outline of your favorite climbing bug or animal. Make sure the widest point of thecreature’s body is at least 7cm across.
2 Decorate and cut out your creature.
3 Using Scotch tape, stick the straws in the shape on an upside down V on the back of your creature.The straws should be about 1cm apart at the top end of your creature, and about 5cm apart at the bottom.
4 Cut a piece of string 4m long. Thread the string through the straws so the two ends of the string hang down from the widest point of the upside down V below your creature.
5 Place a pencil through the loop of string at the top of your creature. To make your creature climb, one person needs to stand a stool or high surface (parental supervision advised), while holding onto each end of the pencil. Meanwhile, a second person holds the dangling ends of the string – oneend in each hand. Pull down on one end of the string, then pull down on the other. Continue doing this and watch your creature climb up the string.(Pictured above.)
The string in your climber looks smooth, but if you were to look at it under a microscopeit would look rough. When you pull down on the string it grips the edge of the straw with friction, and pulls your animal higher and higher. If you coat your string in oil you will find that the animal doesn’t climb, as the surface of the string is too smooth. This is called lubrication.
Ben Bravery and Tim O’Mahony work for Beijing-based Kexue Communications.They perform science shows and workshopsfor schools, birthday parties and otherfunctions. For details, visit www.kexuecommunications.com, e-mail email@example.com, or call 8415 5034.