How do fish float? How do birds fly? How do frogs jump?
These are some of the questions we have been exploring as we added to our animal science studies by examining the science behind animal movement, and it has led us into some pretty complex concepts for 2nd graders. Need I say it? The Gemstones LOVED it!
We explored buoyancy, density and displacement while trying to figure out how a fish bladder works. We soared into the realms of scientific method with some lift experiments that introduced us to the Bernoulli effect, and the place was hoppin' as we measured our own jumps and body lengths and compared our number of body lengths jumped to some "long distance leapers" like grasshoppers and fleas.
As always, our starting point was a wonderful book, which talked about how animals are adapted to move in different ways:
We read it in parts, and then got busy ourselves:
SWIMMERS and FLOATERS:
We ask a lot of questions around here. After reading the book, we understood that flippers and fins are adaptations that help animals swim, but we wondered how fish manage to stay floating in water at different depths. That led us to wondering what kinds of things float. So, first, we experimented with some different objects we found around the classroom - feathers, wood, marbles, etc., and we noticed the similar characteristics of things that floated vs. things that sank. What we noticed: things that floated had holes or held air, while things that sank were HEAVY. This led to further questions...
How heavy is WATER?
Is it heavier than rocks?
I wonder how many rocks it would take to sink the bowl?
Why doesn't it sink right away?
What is happening to the bowl? What about the water level?
Does foil float? Does the shape matter?
How can we simulate how a fish floats? Does it have air inside? Will an eye dropper float? What if it is filled only with air? Filled with water? Can you get it to float in the middle?
What happens if you put pressure on it?
Through our explorations of all these questions, we learned a lot about density, displacement, and buoyancy:
Finally, we learned about fish bladders and how they help fish control their buoyancy levels -- just like our eye droppers!
Next, FLIERS and GLIDERS:
The question here - how DO birds fly? We know they have light bones, and feathers. But how exactly, does the flying thing REALLY work?
We decided to see what happened when we dropped a piece of paper, and noticed that it tended to "swoop" instead of falling straight down. Why?
What happens if we blow right above a strip of paper? Before starting, we hypothesized about what we would see, and many of us were surprised because we thought the strip would go down, but instead, it lifted UP!
We wondered what was making this happen, so we tried a few other things:
Could we blow a dime onto a plate?
Would the balloons move together or apart when we blew through the middle?
Can we keep a card on the end of a spool by blowing through it?
Keep a feather in the air? All of these helped us to understand the Bernoulli effect - that faster air has lower pressure than slow air, so it creates lift.
And finally ... the HOPPERS and JUMPERS.
For the answer to this question (How do frogs jump?), we joined forces with the Navigators for a fun and informative "math adventure."
First we made a prediction about which one of the creatures shown above could jump the farthest.
Then we measured our height...
and how far we could jump.
Then we tackled some division to measure the body lengths we traveled in one jump.
We could not believe it when we realized that we could barely jump the length of our bodies once, while a Springtail can jump 200 times its body length!
