Why do this problem?
gives children practice in drawing straight lines with a ruler, and offers opportunities for learners to identify and talk about properties of shapes. The creative aspect of the task means that children must make their own decisions, and thus the finished product becomes their own.
You could introduce this task by beginning to create an image on the board, working as a whole group. You might ask individuals to draw lines in turn (either using a straight-line function on the interactive whiteboard, or using a suitable ruler) and then, once there are a good number of lines, invite everyone to look carefully at the image that has been created. Suggest that pairs talk
about what they see and then open it out to a wider discussion (think-pair-share).
Listen out for children who describe the shapes. Some may recognise and be able to name 2D shapes with which they are familiar but this could be a good opportunity to introduce correct vocabulary if children are describing shapes using the number of sides or corners (vertices). You could shade all the triangles, for example, in the same way and ask learners if they could work out how you
have decided what to shade.
At this stage, encourage the pupils to create their own pictures, drawing the lines for themselves and deciding upon their own way of colouring/decorating the shapes. You can take this opportunity to observe them as they work and to talk to some of them about their pictures.
Leave time for all the children to look at everyone else's work and invite them to comment or ask questions of each other. The pictures would make a lovely classroom display.
Tell me about your picture.
What shapes can you see?
Which shapes are there most of?
Which shapes are there fewest of?
How will you colour/decorate all the triangles/quadrilaterals ...?
Some children might be motivated to create pictures which satisfy certain criteria. For example, can they create more triangles than their first picture, or a shape with more sides than any on their first picture? They could produce a 'key' to accompany their picture.
Some children might find it helpful to write the number of sides of each shape lightly in pencil in the centre of each one.