Resources

Large display (see weekly plan) with marker pens. Plastic or card shapes.
Individuals record work on a centimetre grid attached.

Revision / oral

What is special about a square? Are these squares? Why / why not?

What is the sum of the angles?
What are the angles of the rhombus?
How can we measure them?
Is there a name for all of these shapes?

Pupils may recall using the Roamer. Ask them, 'What did it do? What command did you give it to make it do that?'

Key vocabulary

Square, rectangle, rhombus, quadrilateral, command
FD (forward), BK (back), RT (right), LT (left), CS (clear screen), REPEAT

Main activity

On the large display, demonstrate FD 25. Repeat this, then RT 90. What will the turtle do if we enter FD 25 again?

Ask a child to come up and try. Stress the importance of the space between the command and the value.

How can we make the turtle go back to the start? (Turn has to be determined from the turtle's viewpoint.) Alternatively, we could tell it to retrace its steps. Introduce BK, LT.

Select pupils to work on available computers. Give them the How to... sheet. Others will work on paper. Ask them to draw a 'staircase' and 'flag'. Use the scale 1 cm = 25 turtle units. Record the turtle commands.

Bring the class together again to try their suggestions.

Look at the flag: what shape is there? How was it drawn? There is a quicker way. Show how to draw a square with REPEAT.

Support

Work with a group using the Roamer. Remind them of the commands and the different step size - forward 1, not 25! Move round a square - pace it out ourselves first. Focus particularly on which way the Roamer needs to turn when it is facing you. For example, turning it to your right means a left turn for the Roamer.

If plastic or card shapes are available, children may trace their fingers round the edges to 'feel' the corners.

Challenge

Design other 'paths' which include squares:

Plan on paper first, using the scale 1 cm = 25 units.

Plenary

Individuals report on their work. Try their ideas.

What will happen if you try:
REPEAT 4 [FD 50 RT 45]
How could this be modified to draw - which shape?

Arrange for all to try out their work on the computer before the next lesson.