If you’ve studied biology in school, there’s a good chance you’ve tried to count the bubbles of gas emerging from a piece of pondweed called Elodea placed in a beaker of water. This has been a standard practical used in biology teaching for decades and is still widely used. This video shows how it can be be done better using a different plant, Cabomba, and how using different approaches allows students to learn about different aspects of photosynthesis.
As well as being a science geek, I’m a magic geek. I’m not sure if anyone’s done the research on this, but I suspect those are two groups of people where there’s a significant overlap. I’ve got an entire live science show I do based around my love of magic and my somewhat lame attempts to become a magician and I include this demonstration as a highlight in the show. Like many of the demonstrations we’ve filmed, I don’t think video can do justice to how amazing it is to see in real life – it appears to be genuinely magical and always gets an “ooh” from the audience.
I’ve used the iodine clock in class purely for the effect it has of enthralling my students, but, as I hope the video shows, it can be used to achieve particular learning objectives. Mind you, I hope it’s clear that we at sciencedemo.org think “enthusing students” can be a sufficient justification for using a particular demo, if you’re going to take that enthusiasm and use it to help students get more out of your science lessons in general.
This film was produced for the Get Set Demonstrate project. Click through for teaching notes, and take the pledge to perform a demonstration to your students on Demo Day, 20th March 2014.