Science Fair!

 

One of the homeschool associations in our state has been holding a science fair each winter for the last several years.  Repeatedly, we had some big conflict and couldn't go.  Finally, the stars aligned at we were able to participate.

Choosing topics was more of a challenge than I'd anticipated (note to other parents who have yet to do a science fair--budget some time for this part).  Especially in the experiment category, it can take some time for kids to wrap their heads around what exactly constitutes a scientific 'experiment.' Volcano models are not experiments.  Leyden jars by themselves are not experiments.  Making a really cool structure using physics is not an experiment.  Proving the existence of standard deviation through trial and error is not a science experiment.

After the difference between demonstration and experiment is fully appreciated (as well as the difference between science and pure mathematics), the feasibility of actually doing the experiment kicks in.  While a giant lab may be able to test for appetite stimulants chemically, we may have difficulty.  While universities may be able to attract scores of human subjects for psychology tests, that may be more challenging for us--who have now whiled away two weeks trying to come up with a topic.  If Scientific American claims they have instructions for a 'cheap' quantum entanglement machine, the $400-$500 dollars required may not be in family's science fair budget (never mind the fact that in would mean bringing radio active material into the house and the hoped for experiment would require two such machines).

Moving on...

Perhaps the trickiest part of coming up with a topic is restraining yourself and allowing the kids to do it themselves.  There is a fine line between enabling a child and doing something for them.  One of the hardest (and most neglected) aspects of parenting in the 2010s is letting kids do things for themselves.  It means the freedom to fail.  It also means increased opportunity to learn.

Finally, the kids came up with topics they liked and that we could actually do.  

Solomon and Nova both entered the Science Experiment Category.



Nova tested Little Caesar's Pizza for appetite stimulants using rats and humans.


Below is Nova's explanation of her experiment, written in preparation for her oral report.

This experiment used five humans and three rats to answer this question: why do we eat so much Little Caesars pizza. If you compared the number of pieces of Little Caesars pizza you ate in one

sitting to the number of pieces of home made, you would be in for a big surprise. Just think about how much more you order. My hypothesis was this: Little Caesars pizza has appetite stimulants in it. To test this theory, I monitored the diet of five human subjects and three rats so it could be exactly replicated the next day. They could eat whatever they wanted until lunch, but they had to tell me what they ate and when they ate it. At lunch, three cheese pizzas and a sausage were ordered. One piece was weighed, marked, and given to the rats. I weighed each piece eaten by the human subjects and marked the weight in its respective column. 


The next day was the same,except for the pizza, Instead of Little Caesars, we had home made. So, why do we eat so much Little Caesars pizza? The answer is: we don't. According to the data, the majority of the human subjects ate more of the home made pizza. The rats ate the same both times. But the strange thing about the data was that, even though we had eaten more of the home made pizza, we had eaten more pieces of Little Caesars. This shows that little Caesars is significantly less dense than home made pizza. This is my theory for why the hypothesis was incorrect: Little Caesars pizza is less dense than the what we make at home, so we had to eat more pieces of it than the home made pizza. This created the illusion of eating more, because we generally measure pizza in number of slices, not weight.



Solomon tested the viscosity of non-Newtonian fluids at different temperatures.  Below are excerpts from his paper.

Abstract: 

This experiment was based on the hypothesis that non-Newtonian fluids, and in particular shear thickening substances, would increase or decrease in viscosity in response to increases or decreases in temperature.  So, as a method of measuring viscosity, the substance was timed flowing through an aero press coffee maker.  Three data points were taken, one with a higher temperature, one with a lower temperature, and one at room temperature.  The results supported the hypothesis, as viscosity increased greatly when the liquid was cooled or chilled, and decreased comparably when it was heated.  

Application: Shear thickening fluids have two main applications.  One is in body armor, allowing treated Kevlar to absorb far greater impacts with far fewer layers.  The results of this experiment have very little relevance to that field.  

They are more relevant to the second application.  Such substances are used in some four wheel drive on road vehicles, as a passive system to automatically engage or disengage four wheel drive as circumstances dictate.  If temperature affects viscosity, then knowing this could be useful in predicting how these vehicles might perform in extremely high or low temperatures.  

Discussion:  The hypothesis was correct, as shown by the data gathered.  Temperature had a far greater impact than expected, causing it to speed up by approximately five times it's current speed when heated, and flow six times slower when cooled, comparing both to room temperature data.  While the experiment was effective and genuine, and generated usable data, there are ways it might be improved.  This would include taking data from a wider variety of temperatures, using more than one type of fluid, possibly including something shear thinning.  It might also be improved by ensuring that all instances of the experiment used the same brand of corn starch.

This experiment's goal was to establish whether or not temperature is a significant factor in determining the viscosity of shear thickening fluids, and it did accomplish that.  By making these alterations and running the experiment again, more detailed data could be gathered to determine the exact increase in viscosity in correlation to an increase in temperature, though to do this to an effective extent would require equipment or methods able to accurately raise and hold the substance's temperature by only 1 or 2 degrees, and those are not commonly available.  The other recommended improvements would only improve and expand the data gathered from a similar experiment, should one be performed at any point in the future.

It should also be noted that an attempt was made to heat the substance on the stove.   Do not attempt this.  There were some mild concerns it might thicken as water boiled away, but long before it would have boiled, it thickened and congealed.  It appears that when heated on the stove, the substance actually cooks.  Hence the recommendation; do not attempt to heat the substance on the stove.

Charlotte entered the Science Report Category.  She studied lightning, and did indeed get to make it at home--her top request.  We learned about sprite lightning, ball lightning, fork lightning and sheeting lightning.  Tesla's amazing discoveries and inventions were also part Charlotte's research.  She made a leyden jar, getting several sparks to jump from the plate to the nail bottle, storing the
charge in the saltwater below.

In Charlotte's own words (taken from her poster):

What is Lightning?

Lightning is static electricity.  It forms in a cloud.  The ice crystals and rain drops that make the cloud crash into each other, making them positively and negatively charged.  If they are opposites, they want to join together, if they are the same, they want to split apart.  Once they join they strike out and make a beam of lightning.  A streamer is a positive beam from the ground that hits the negative leader stroke from the cloud.  And if they join together then it makes a return stroke and creates lightning.

We tried to make lightning at home.  

First we took a plastic fork and cut off some tin foil and wrapped it around the fork. Then we took a balloon and scrubbed it on my hair.  We touched them together and it made a spark.  We could hear the spark, and in the dark we could see it.  It looked like a beautifully silky white string.  

We did another test.  The test was, again lightning, and we used a bottle of sprite we drank earlier.  We wrapped half of it around with tin foil and we filled it up with salt water.  We put a nail in the center of the cap, not all the way in, and screwed it on the bottle.  We took a tin foil plate and a styrofoam cup and then we taped them together.  And then we had a styrofoam plate.  We took some wool and then we um a rubbed it on the styrofoam plate.  We put the tin foil plate on the styrofoam plate.  They stuck together.  We took them apart carefully, not touching the tin foil plate.  We touched the tin foil plate with the nail and made static electricity.  We heard a loud click right after we touched the tin foil plate to nail.  

Her brother's plasma lamp provided a fun way to play around with plasma, the substance most scientists think make up ball lightning.  

All three kids had both a writing component and an oral interview with a judge.  Charlotte was very nervous but did beautifully, convincing the judge she was brilliant (she thought Charlotte was in 3rd grade instead of 1st).  Solomon and Nova also did very well, both earning blue ribbons.  Solomon wowed the judges,  also earning the runner up grand prize, a yellow ribbon (though my camera had died by that time, so there is no picture).  

They also fiddled around with the engineering challenge--rubber band cars that could carry a one pound load.  Though they worked on them for several weeks, in the end only Nova had a car that could move forward holding the one pound load of baking soda.  She felt it was not up to snuff and left it at home.  It turns out only one other kid brought a rubber band car--it was a challenging task. She sorely regretting leaving hers at home.  A lesson learned.

Aside from presenting their own experiments, the kids had fun seeing what everyone else had to present.  Topics included testing to find the best detergents and cookie recipes, the effects of exercise on humans, the effects of music on rats, which type of paper air plane flies the farthest, which super ball bounces the highest, changing the course of ants in the Amazon, the physics of ice skating, tests on the persistence of vision, and how prisms work.