A scientific hypothesis. Which is a correct question to ask during experiment?

[amselby81]

I know what a hypothesis is, but when doing a science experiment, which is the correct question to ask to find a student's hypothesis? We're doing an experiment on why fish float belly side up. (Yes, this is for Classical Conversations, haha!) We're filling a plastic bag halfway with water and half way with air, and seeing whether the bag floats air side up or water side up. When asking a question to find a hypothesis, do I ask why they think a fish floats belly side up, or do I ask whether they think the bag will float air side up or water side up?

 

I'm just not sure if the hypothesis is guessing why fish float belly side up, or if it's guessing what will happen with the experiment. I hope that makes sense. Thanks!

[MrsBanjoClown]

Which side the bag will float on. A hypothesis will always predict what is going to happen, not why it happens.

[amselby81]

Thank you!

[daijobu]

This probably more than what you were looking for, but it raises an important point about the importance of how to write a good scientific hypothesis. I am copying this explanation from someone else's homeschooling blog:

 

"Another big problem is one I lay at the feet of the teachers. Few students have any idea what a hypothesis is. Almost all of them think that it is a random guess about the outcome of some predefined experiment, but a hypothesis is not a guess. It is a prediction from a theoretical model of what is happening. For a hypothesis to be meaningful, there must be at least two competing theories of what is going on, and the experiment has to be designed so that these two theories result in different predictions (different hypotheses) in the context of the experiment.

 

For example, if we were interested in the effect of temperature on the bounciness of rubber balls, it would not be good enough to randomly guess that warmer balls would bounce higher or less high. One needs a theory of bounciness that would predict a change in bounciness. For example, if one were considering tennis balls, one might predict that warmer tennis balls would have a higher air pressure inside, and hence be stiffer, causing less frictional loss from flexing the rubber of the ball, and hence bouncing higher. But for solid balls, the warmer ones might be less stiff, due to softening the material, and hence bounce less high. The theory comes before the experiment design!"

 

You can read more here: http://gasstationwithoutpumps.wordpress.com/2012/02/06/science-fair-time-again/

 

This is probably overkill for your young kids, but it's good to keep in mind for the future.