Human graphs! Using students to represent themselves on a large graph, videoing it and playing back to the students. Then they have to recreate the graph on paper. This technique could be extended to coordinates, plotting graphs, constructions, transformations, etc.
This is an idea I got from another teacher at a NCETM regional network meeting. He had videoed his class forming scatter graphs from a room on the top floor of a school building. He had marked axes on the ground and used the students as points on the graph.
Here's how I did it.
As the class came into the room there was a 30cm ruler on each desk and a PowerPoint presentation on the board displaying how to measure hand span. There was also a sheet with spaces for "my hand span" and "my shoe size", together with a blank table of results. Whilst I did the register, the students measured their hand span and wrote it on their sheets. After this they wrote the size of the shoes they were wearing on the sheet.
We then went to an area outside, where there are square paving slabs, and which is overlooked by a third floor Maths classroom. I labelled the sides of the area with numbers to represent shoe size (1 to 9 horizontal axis) and hand span (13 to 22 vertical axis).
First I asked the students to to stand adjacent to their own handspan, one per slab filling in from the axis. Thus forming a human bar graph (horizontal). They then lined up next to their shoe size, forming a vertical bar graph.
Finally I asked the students to stand adjacent to both their handspan and shoe size. We discussed the shape of this graph, and some students knew it was a scatter graph.
After this rehearsal, I went up to the third floor room and videoed the group forming the graphs. We then went back into my classroom and played the video on the whiteboard. We collected all the data on the sheets as a group. The students then had to recreate the graphs on squared paper using crosses to represent each person.
Discussion about the graphs then followed, including about numbering axes, discrete and continuous data, different types of chart, including pie charts, and what they can be used for.
The following lesson looked at formalising these types of graph and drawing pie charts, and interpreting them.
The approach was very successful, particularly highlighting that on a scattergraph each point represents a pair of data for each object/person/etc.
This technique of videoing from above could also be extended to other topics!