Knowledge and Understanding
 : Crane 
Approach: One to one
Level: Year 4 and year 8
1.3Mbk
Resources: Board with cogs, handles, and drum for string with hook, weight to be lifted on hook.

Questions/ Instructions:

In this activity you will be looking at a model and
telling me how it works.

On this board there are two black handles.

 

% responses
y4
y8

Show the student the two handles.

Without touching the board, tell me which handle you would turn to make the string move more quickly, and which handle you would turn to make the string move up more slowly.
Correctly predicted faster handle

44

48

Now try turning the handles and see which one makes the string move up the more quickly.

Teacher may need to hold the board steady for the student at the edge of the desk so that it doesn't tip.

Correctly observed faster handle
64
72

Tell me why you think that turning the big cog makes the string move up more quickly than turning the little cog.

Point to particular cogs.

Now we have a heavy weight to lift on the hook. Which handle do you think it would be best to turn to make it easiest to lift the weight. Tell me without trying it.

Why do you say that?

Now have a go at trying to lift the weight by turning the handles.
Have you changed your mind about what you think?

Crane image

Explanation for faster handle clear
vague
no idea

6
41
53

24
37
39

Commentary

Difficulty was experienced with the equipment for this task. Friction and wobbling cogs led to unreliable results for the second part of the experiment (related to lifting weight). Results for that part are not reported.
 
[ top of the page | Technology Report 1996 ]