Science & Art Fair 2011 :: Our Science Entry - Eva Varga

April 6, 2011
Despite the fact that I was the one organizing the Science Fair and that science is my strong suit, we seldom found the time to sit down and do our science fair project.  Our original project was derailed due to weather and logistics (we wanted to do a maple syrup project … but we live in central Oregon and Sugar Maples (Acer saccharum), a species of maple native to the hardwood forests of northeastern North America, are hard to find.  This left us with little time to see a project through to completion.

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.


2 betta fish
2 small glass jars
2 large glass bowls or jars
2 thermometers
1 pocket watch or timer
pencil and paper to record data 

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. ]

We discussed our results upon completion and were quite surprised by our numbers.  The two fish had significantly different gill beat rates.  Meili wrote, “After I was done with my experiment, I looked at my data.  My results showed that the gills beat the fastest in cold water, at about 77 beats per minute (bpm), an average of 66 bpm in hot water, and an average of 64 bpm in room temperature water.   My hypothesis was not correct though because the gills beat faster in hot water too.  They beat the slowest in room temperature water.  I think this is because they were stressed.”  We talked about how a larger number of fish to test would help to give us better results.  We also wondered if the species of fish would make a difference.
[Admin Note :: Due to procrastination … we were unable to type up our project and create a display board as we would have liked.  Our printer had somehow stopped talking with our computer – a glitch I wasn’t able to overcome – and we thereby had to print at the library at the last minute.  Even then … we forgot to include our data and to create a graph … producing a display that was sub-par.  Oh well … this allowed us to learn from our mistakes as well.  Another lesson learned.]
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