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"Let us strive to make each moment beautiful."
Saint Francis DeSales
painting by Katie Bergenholtz

The Difference Between a Science Demonstration and a Science Experiment


For our mummification experiment, the apples are waiting for the different substances we will add.
For this week, I thought I would show you the experiment we are currently working on, and to talk a little about one of my biggest pet peeves...the difference between a science demonstration and a science experiment.
Sam wrapping his mummified orange/potato in gauze.
While studying Ancient Egypt a few years ago, we mummified oranges and potatoes. Although my youngest participated in that, he wants to do it again since he was so young when we did it before, so we will be mummifying oranges and potatoes using table salt and baking soda for the natron the Ancient Egyptians used.
But this year, I thought I would add an science experiment in addition to the the mummification project.
I have seen this done many times on various blogs. We took six plastic disposable cups and put an apple slice in each one. 
In one we added 1/4 cup Epsom Salt.

In one we added 1/4 cup Baking Soda.

In another, 1/4 cup table salt.
In two cups we added a combination of two substances; one we added a mixture of a 1/8 cup Epsom salt and 1/8 cup Baking Soda...
and in the other a combination of Table Salt and Baking Soda.
In the last cup, we left the apple alone, and labeled it "Control."
A control is part of a scientific experiment. It is a portion of the experiment that is separated from the rest of the experiment. This isolates the independent variable's effects on the experiment and can help rule out alternate explanations of the experimental results.
source: Science Fair Coach

I call a science activity that complies with the scientific method, "an experiment." If the activity does not comply with the scientific method, then I call it "a science demonstration." I have seen lots of science books that do not use this rule, and call demonstrations, "experiments."

Although technically an experiment can include personal and informal demonstrations, such as a cola taste test in

order to determine what tastes the kids like best, I think it is important to begin early establishing the difference between the orderly proving of a scientific conclusion and an observation. Both are important to do, but they are quite different and talking about the difference from the beginning is a simple and important way to teach the scientific method.
An easy way to tell the difference is to ask yourself, does what we are doing prove a scientific principle or does it just show one?
For example, the process of Extracting DNA from Strawberries is a great, fun demonstration, but it does not prove that what you see is DNA. You have to take our word for it.
This experiment, on the other hand, complies with the scientific method, and is, therefore an experiment.

Step 1: Ask a Question: What substance dries up an apple slice quicker and more thoroughly? This is not the greatest question because qualitative in nature. A better question would include some method of measuring the moisture left inside the apple slices.

Step 2: Make Observations and Conduct Background Research: We have learned that the Ancient Egyptians used Natron to dry out their mummies. We have also learned that Natron was mostly sodium carbonate. What do we have on hand that we can use to dry out an apple slice and simulate Natron?

Step 3: Propose a Hypothesis: We got together Epsom Salt, Table Salt and Baking Soda and we made our educated guesses about which would work the best.

Step 4: Design an Experiment to Test the Hypothesis: We tried to make the slices the same size and we tried to make everything except the substances added to the cups exactly the same. It would have been better if we weighed the slices and made them exactly the same, but I let that go.

Step 5: Test the Hypothesis: Since some of us hypothesized that a combination of substances would do the best, as Natron really is a combination of ingredients, we had to include combinations of the substances as well. We made sure that we have the same amount of the ingredients; the all equaled 1/4 cup.

Step 6: Accept or Reject the Hypothesis: We haven't arrived to this step yet, but we are prepared for it!

Step 7: Revise a Rejected Hypothesis (return to step 3) or Draw Conclusions (Accepted): We are all anxiously waiting to come to this step.

This all is not to say that demonstrations are not as good. In fact, most of the science explorations we do, especially in the pre-high school grades are demonstrations. I just think it is important to know the difference.

9 comments:

  1. What a fun idea to change things up. Thank you for hosting Science Sunday, Phyllis!
    Well said on the difference between a demonstration and an experiment. I know I am often guilty of mixing up the two. You've explained the difference very clearly. I resolve to be more accurate from now on!

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  2. Good point, Phyllis! I've never really given it much thought before. This post ties right in with what Jerry has been learning about! The scientific method and ancient history!

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  3. I ran out of time to get ours up, so I'll for sure have one on Sunday, maybe more depending on how much writing I get done this week.

    I think I often get the two mixed up in our discussions, we do lots of demonstrations, but not as many experiments.... Thanks for the reminder on this.

    And I love your experiment here. I can't wait to hear what is most effective.

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  4. I love the switchup - fun! And I definitely am guilty of using "experiment" interchangeably with "fun thing to watch" even though I know the difference - and you make a great point about really understanding the scientific method!

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  5. Being of the easily confused persona, please bear with me. Do I still link to science Sunday at Ticia or to you? I've done it to Ticia, I hope that's okay?
    I love your new header. A really, really lovely photo.
    In fact, I could probably include Alkazan post in the history link up as well and link back to you also. That's what I'll do. Okay, all's well with my world now!!

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    1. For the month of January, link up science posts at All Things Beautiful and History and Geography posts at Adventures in Mommydom. I am sorry it was confusing. We just thought it would be fun to switch them.
      Thank you about the photo. Katie took it.

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  6. for how long do you leave the apples there for?

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  7. for how long do you leave the apples there for?

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  8. for how long do you leave the apples for?

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