Videos of experiments

Frame from video showing adding a reagent to a test tube

The still above was sampled from a DV camera recording of a chemical demonstration by the irrepressible (incompressible?) Dave C . The still is reduced in size by 50% from the iMovie video capture – the frames come in at 784 by 576 pixels on the particular JVC DV camera we were using. iMovie and Windows Movie Maker both make it possible to grab frames as stills, and this facility could help produce MS PowerPoints for flash slide shows of lab procedures so students can see what things look like. A short PowerPoint showing visuals of the steps might be useful especially for evening class students who usually only get one attempt at practicals.

Sound is basic from the video camera; I had the Olympus digital voice recorder and an external microphone set up to catch the commentary as well and the quality is much better with the separate recorder. I’m planning on editing the video clips to the sound track as a guide so that the small clips I sampled from the DV camera will provide a visual demonstration of the points in the commentary. I did two takes, one with a wide frame and a second with zooms onto the test tubes and reagents. Cross cutting and some stills to cover the transitions will handle it.

When importing the clips into iMovie from the DV camera, I sampled short sections of about 10 to 30 seconds to give as much leeway as possible when editing. This is almost ‘editing in camera’ and I may need to resample from the DV tape to get the best clips. I find iMovie easier to use than Windows Movie Maker on a good spec XP laptop. I need to know both so time will tell. The iMovie project file comes in at 3.7 Gigabytes so I’m glad of the external hard drive.

Videos of classic demonstrations will be useful for evening and weekend students who miss the actual event, and for review and revision.

Silver precipitating out of a silver chloride solution after exposure to sunlight

The image above shows how the Silver Chloride precipitate clears when exposed to sunlight – the grey deposit at the bottom of the test tube is silver. This reaction is close to my heart as it is the basis of photography.

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