Investigating machine movement
Objectives
- Create and debug simple programs
- Use logical reasoning to predict the behaviour of simple programs
- Recognise common uses of information technology beyond school
Resources
Recap last week’s lesson and how they made their WeDo birds move. How did we program them? How do you create an algorithm with WeDo?
Set their model from last week up with the computer again. Explain that this week they will be completing an investigation into how the birds move and also creating longer algorithms to make the birds do more.
Ask the children to recap what makes the birds move (if you discussed it last lesson). Start with the program on the computer being sent to the power pack via the USB, then that being converted into movement from the motor, which turns the small cog, which turns the bigger cog, which turns the green wheel, which drives the rubber band around, which drives the other green wheel and the cog behind it. Both the large cogs turn the downwards facing cogs which make the birds turn.
Why is the rubber band a really important part of the model? Only one bird would move without it.
Introduce the investigation sheet. Explain that the band can be place in different places and arranged in different ways which will change how the birds move. For example the first illustration on the sheet shows the regular setup for the band that they should already have in place, how can we describe the movement of the birds when it’s setup like this? What does bird 1 do, what does bird 2 do? Point out the words at the bottom of the sheet and encourage them to use them in their explanation.
In their groups they must then try out the second and third illustrations on the sheet, as well as designing 2 other set ups themselves and for each one, explain how the change affects each bird’s movement. 
Discuss and review what effect the each setup had on the birds.
When they have completed the investigation, click through the build instructions and example algorithms in the WeDo software until you get to this longer algorithm:
What do they think ‘Random Input’ means? Which bit of the program represents ‘Random’?
Ask them to build this and test it. Can they then explain what is happening to their model and what each part of this algorithm does?
Finally, ask them to write three of their own algorithms that begin when keys on the keyboard are pressed. There are extra blocks that are initially hidden that can be revealed by clicking on the small grey arrow in the bottom left of the WeDo screen, this will reveal all the blocks.
The yellow block with an A key on it can be set to any key by adding it to the WeDo screen, clicking on it, then pressing the key you want to use. The image should change to show the key you have selected.
Tell the students their algorithms must include:
- Movement
- Sound
- A speed setting
Their algorithms might include:
- A repeating block
- Randomisation blocks
- Waiting blocks
Finish off by asking some groups to demonstrate what they have done and how it works.