Fortunately, I have a wealth of short projects that can be completed in approximately 45 minutes – one of the benefits of being a former science specialist. I thereby described a project I used to do with my fifth grade students – goldfish gillbeats – and both kiddos were intrigued so we proceeded forth. We gathered our materials – but rather than buy goldfish, we opted to use the two betta fish we already owned – and our experiment was underway. Our goal was to answer the experimental question, “How does the temperature of the water affect the gill beats of a betta?”
Before we began, I asked each of the kids to write their hypothesis in their notebooks. Meili stated that she expected the gills to beat faster in cold water because they would have to work harder to get the molecules moving and across their gills. Buddy, on the other hand, hypothesized that cold water would slow down the number of gill beats because they would be hot and when you get hot you breathe more.
Procedure & Setup:
Our set up involved placing each fish in a small glass jar with room temperature water (essentially the water from the fish bowl). We recorded the temperature of the water and then counted the number of gill beats for 1 minute for each fish. We counted again twice more to get an average number of gill beats.
We then carefully placed each small jar into a larger bowl of hot water (and later ice cold water), essentially creating something like a double-boiler system; though we weren’t heating the water – we just used hot tap water (and later cold tap water with ice cubes to bring the temperature down even more). We recorded the temperature of the water and then counted the number of gill beats for 1 minute for each fish. We counted again twice more to get an average number of gill beats. These numbers were recorded in our notebooks for each fish.
[Admin Note: In the classroom, when I have done this with a class of 30+ students, we have a significant population sample and can more easily compare/contrast experimental design flaws, etc. ]
