Projecting onto the whiteboard, video of a demonstration as it happens. Examples include, constructions, using a calculator, reading scales and drawing graphs. This technique can be applied to any situation where you want to demonstrate something that would otherwise by too difficult for the whole class to view sensibly.
I first used this technique to teach a group of year 7's about reading scales. I wanted the students to read from actual measuring instruments, not just scales drawn on paper.
I'd found various measuring devices at home an around school, bathroom scales, kitchen scales, thermometer, measuring jug, bucket, ruler, metre stick, etc. Each had different scales, used different units and different divisions. The students were organised in groups and had 5 minutes to visit each station. Each station had a measuring device and something to measure. At the end we all compared results and discussed reasons for differences.
I then used my digital camera (actually my photo camera not video camera) connected to my digital projector to show the students how to measure the objects and use the scales, highlighting the misconceptions and errors that had been made on the task.
As I was using my stills camera I didn't video this, but it could be videoed, then used in other classes as demonstration, (as could all the ideas in this section). I do have some of the still images I took of the students measuring though.
I got this idea from a NCETM network meeting, talking to Marie Darwin. She had videoed demonstrations of the standard constructions for students to use in class and for revision. I thought that this topic would be ideal for video demonstration, as I've never been happy with board compasses! I set up the video camera on the back of my chair and projected the image into my whiteboard as I demonstrated each construction as the students worked with me.
Using a calculator
When teaching calculator techniques, or topics that require ascientific calculator, I often find that the students have calculators that work in different ways. "I can't find that button on my calculator!" or "It doesn't look like that on mine!" are common interuptions to these lessons.
When I was teaching a year 10 class to calculate with standard form, I contemplated using an emulator on my whiteboard. However, I thought about the Different calculator problem, so I found all my calculators from the past 20 years! and used them to demonstrate standard form on the whiteboard via video.
Drawing graphs (Drawing axes!!!)
I'd been teaching linear graphs to my Year 9 group and found that they could calculate the y values from an equation and draw up a table of x and y values. They were fairly good at plotting the points if I gave them a printed set of axes. However, if I asked them to draw their own axes, I often got the question, "why isn't my graph a straight line?". On inspecting the work I found that everything was right apart from the drawing of the axes. the distance between 0 and 1 was 1cm, but the distance between 1 and 2 was less and the distance between 2 and 3 more!
So when I approached plotting quadratics I used a video demo!