How to Design an Experiment to Get Fair Results
The beginning of every science course from K-12 starts with the scientific method. Once my students are in high school, we skip the formalities and go straight for the new content. Even though professionally I’m a science educator, we teach science in an out of the box way. How to Design an Experiment to Get Fair Results is essentially the scientific method in action. Keep reading to learn how we engage our kids to answer questions they have and how we apply that when we’re doing STEM Activities for Teens.
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Note: We did this particular experiment to answer a simple question in 2008 when our kids were 9, 7, 5, and 2. The originals posts here on the blog are from 2008 as well. So, although this was before high school, it was legit stuff and a great example creating a fair test experiment for any high school science course. Also, the original post pictures did not survive all of my website transitions and upgrades, so I improvised by taking pictures of the originals in my scrapbook. So, bear with me and let’s get to it!
Science is about Answering Questions
When they can think for themselves, make connections between disparate bits of information, observe with interest, ask their own questions and unashamedly follow an interest in any direction, they are in league with some of the greatest scientists in history. -Laura Grace Weldon, Free Range Learning
Back in my homeschool convention speaking days, I used to do a talk on doing science in your homeschool. So many time I hear that moms “don’t get to the science”. It’s hard when you don’t particularly like science and the lessons/materials don’t feel accessible. In other words, it takes a lot more energy to pull that off.
We often think we have to have all the ducks in a row before we can start anything and there’s so much that can distract us from wrangling those ducks together so you can do whatever it is you are collecting ducks for.
In it’s most distilled form, science is about answering questions. Answering questions doesn’t feel as ominous and big.
I jump on the things my kids ask that could be turned into an experiment. It doesn’t take much. All you need is the question they are trying to answer and some time to get things going. In short, when they ask a question we don’t know the answer to, we find out. We even do this when we know the answer and we’ll help them to find out.
We Wanted to Know Which Popcorn Was the Best
We recently ordered seven types of gourmet-ish popcorn (mainly because Alton Brown of Good Eats convinced Dan it was the best thing to do for popcorn!) and we’ve been saying that we need to do a taste test each time we try out a new kind.
When I found out that today was National Popcorn Day, I knew today would be the pop off! We talked to the kids about how to test the popcorn types fairly.
- What things would need to be the same and what could change if we wanted only to find out how the popcorn measures up to the other types.
- The kids unanimously decided that the amount of kernels we start with must be the same along with the amount of butter and salt.
- That way the only thing different is the kernels we start with.
- They decided that we’d measure the size once popped (by how much it fills the same bowl), taste, and color.
- Each type of popcorn will receive its own score between 1 and 4 and we’ll do some data analysis to determine the winner.
- Should there be a tie, we will do a taste off between them and you must pick one as better than the rest. If there is still a tie after the taste off, well then there will be a tie (this isn’t college football after all).
The kids are very excited. I’m off to make data charts and we will be sure to report back in later on after the official event. Can you tell these are children of an engineer and science teacher? Nah….
Editor’s Note: Now that all of these kids are adults, only one is looking for a career in a STEM field. However, the other three are science literate and take a very scientific approach to their technical writing, design work, and history studies.
Deciding on the independent and dependent variables is the hallmark of a fair test or a procedure that follows the scientific method. In this case, the kids knew that if we were testing for the best popcorn that all the other variables needed to stay the same and the only thing that would change would be the type of popcorn.
That way, those other things like butter, salt, and oil would not affect the results.
Collecting Data in an Experiment
After deciding on the variables, we got to work with the kids.
- We weighed out 40 grams of kernels for each type on the kitchen scale.
- Dan’s the official popper. 1 tbsp of oil was used in the “pop it on the stove in a metal bowl” method. Don’t ask. It’s all about Alton.
- Ethan measured the volume of the popcorn in a pitcher using the formula for the area of a cylinder and the younger three recorded the number of quarts from the outside using the numbers on the side of the pitcher .
Once the data was collected, it was time to work with our results.
Working with Our Data to Make Some Conclusions
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Making Conclusions Based on the Data
Once you’ve collected your data, it’s time to do some math, to make some graphs, and to draw some conclusions based on our results.
When it comes to forming some conclusions about your question, based on the data, you’ll probably need to work with that data to learn the results.
The kids had the best time and we got to have a first hand look at developing a fair test aka: an experiment using the scientific method.
In our case, the kids:
- Ethan calculated the volume of popcorn- using the data he collected and the volume of a cylinder
- We popped up eight varieties and measured volume and scored taste a 1, 2, or 3 for good, ok and bad!
- Then we made several graphs of our data, either by hand or using Excel (gotta get those spreadsheet skills moving along!).
One of the things we pondered was whether the size of the unpopped kernel would have any effect on the final volume of the popped corn?
By making this graph we were able to practice another step in the scientific process- data analysis. Can we use the raw data we collected and answer any more questions?
This graph took some tweaking because we used more of a qualitative approach to the data when it came to kernel size vs the quantitative calculation of volume.
Another lesson for the kids- which graph best represents our data? Not all graphs are for all types of data.
This information is best served by the all time favorite- bar graph! Kernel sizes were classified as small, medium, or large- extremely precise- absolutely!
So, you tell me…as our unpopped kernel size increased, what happened to the popped volume of corn?
Is there a trend?
You Don’t Have to Have All the Ducks in a Row
You just need to be willing to answer questions with your kids and teens!
When your teen is working on a science problem and they ask why or how or will it, say let’s find out! Then just think about, with your teen, how you can find out the answer using the scientific method.
No time for a worksheet? No problem!
Grab the loose leaf paper and go with it.
In fact, I’m a huge fan of using loose leaf paper!
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