The Scientific Method
Lesson 4 of 9
Objective: Review the steps of the scientific method to familiarize students with the vocabulary and concepts that will enable them to later evaluate and design experiments.
This lesson continues establishing a culture of scientific thinking in class and is intended to review the steps of the scientific method with two main goals:
1. Students understand why the variables in experiments must be controlled and how this leads to more reliable conclusions.
The lesson begins with a warm up to help students see the parallels between the scientific method and their own processes for solving problems. The bulk of this lesson, however, is a teacher led presentation of the steps of the scientific method. Throughout the powerpoint, there are opportunities for student involvement, either with their partners or sharing with the whole class. So even though this is largely a teacher led lesson, it still offers many opportunities to be an engaging, interactive experience for your students.
As far as alignment to the Common Core standard, although the standard specifically speaks of a literary or informational text, the scenarios presented in the powerpoint are an informational source with which students are given opportunities to analyze, reflect, and utilize new vocabulary to develop conceptual understandings of the process of scientific research.
To introduce the lesson on the scientific method, I begin with a typical "problem solving" experience familiar to most students.
The idea of this warm-up is for students to see that the process they follow when solving problems in their everyday lives has similarities with the scientific method:
1. observe the problem
2. think of what might be causing the problem
3. test possible solutions until the problem is solved.
To begin the warm-up, I direct my students' attention to the whiteboard where I have written the following,
"You come home after a hard day of school and all you want to do is watch some TV. Unfortunately, when you pick up the remote and point it at the TV, nothing happens... WHAT DO YOU DO?"
I then ask students to talk with their partner and write step by step instructions for dealing with the remote/TV scenario, including an explanation of what they would do if the first thing they tried did not work.
After about 2 or 3 minutes discussing with their partner, we discuss as a class. Student responses will vary. As students share possible solutions, I write them on the board. After a group shares their first step, I would then open it to the class with a question like, "would anyone else do something different?", and then allowing other groups to share their approach.
However you allow the discussion to unfold, it's important to guide the discussion to a place where students can see that the first solution isn't always the correct solution and they need to "troubleshoot" a solution by eliminating false solutions, akin to a scientist making an initial hypothesis and then looking at the results of experimentation to make conclusions or form new hypotheses. In this warm up, I would do this by asking, "well if that doesn't work, what would you do?", in the hopes that other groups continue to share alternative solutions as a class. Ultimately, I hope students can see early on in the lesson that, rather than simply being part of the scientific method of answering questions and solving problems, experimentation and learning from our mistakes are natural parts of how we learn and solve problems.
In this section, I show the powerpoint covering the steps of the scientific method. This is a longer powerpoint than the powerpoints in previous lessons, so it’s important to pace yourself through the lesson if you want to finish with enough time for wrap up.
Because there is a lot of vocabulary and content to cover during this powerpoint in a short time, I distribute a “fill-in-the-blank” note sheet at the beginning so that students can focus on the emerging discussion and examples rather than furiously scribbling down all the information presented.
I find it important to check for understanding throughout the powerpoint, and though time constraints may require occasionally just asking a volunteer to share their answer, I prefer to ask a guiding question (e.g., "Why would a scientist want to do research before designing an experiment?") and then have students briefly discuss the question with their partner before asking for volunteers to share a response.
This is beneficial for two reasons. On the one hand, it breaks up some of the monotony of just listening to the teacher talk about the topic. Secondly, once students have discussed a question with their partners, it is usually more likely that students will be willing to share their thoughts if they have already gone through a “vetting” process.
As an added bonus, if it’s usually just the same groups of students that volunteer answers, it is much easier to put someone “on the spot” when you can ask, “what did you and your partnerdiscuss?”. There’s just something about making someone the spokesperson representing a discussion rather than the sole responsible party for an idea that may prove to be good or bad.
Think of it as “peer review” for their ideas.
I mention specific moments for checks for understanding under the section headings below.
Identify the Problem:
It’s important for students to understand that the word “problem” here is like a “math problem”, a question that could be answered. I always point out the importance of curiosity in science, reminding students that young children’s learning is driven by curiosity, exploration and experimentation… how do you know a question needs to be answered if you don’t think to ask it?
The example given here is of a tree with leaves that have turned from green to orange. Although I present a question, “Why do leaves change color?”, you may ask students to generate more specific, testable questions, such as “When (what specific time of the year) do leaves change color?”, “Where (which geographic regions) do trees change their color?”, “What makes leaves change color?” (this question could mean which stimuli cause this change and/or which specific physiological processes are at work in the tree when to cause the change in color.)
If you want to extend this segment, you may ask students to each write down an observation (it could be of something in the room or something they have observed before). Then ask students to share their observations with their partners and have each partner generate a question about their partner’s observation.
The section ends with the importance of conducting research before moving on to the other steps of the scientific method. I would make this point here with a question, “Why, as a scientist, would you not seek research funds or design elaborate experiments to answer your scientific question without first doing research?” Answers will vary, but the obvious answer would be, “the question may already be answered”. Hopefully this reminds students of the earlier “What is Science?” lesson about the additive, developing nature of scientific knowledge.
State a Hypothesis:
This section is fairly short and straight forward. Most high school students are already familiar with the term hypothesis, I would just make sure to stress that a hypothesis is a possible solution to a scientific problem, and that scientific knowledge progresses even when we simply eliminate a possible solution.
I would also ask students here why a hypothesis isn’t the same thing as a “guess”. The distinction (which they can hopefully make based on the previous section) is that a hypothesis is more like an “educated guess” in that it is based on careful research and observation.
Another important point to stress here is that hypotheses need to be testable so that scientists can move to the experimental stage of the scientific method. It might be useful to ask students to generate testable hypothesis to the leaf color change example in the previous section (e.g., “leaves change color as a response to changes in temperature” or “leaves change color because of a decrease in the number of chloroplasts in their cells”).
Test the Hypothesis (Experiment):
This section introduces the most new vocabulary, so it may require a bit more time to check for understanding.
When I come to the bulk of the vocabulary (slide 10-11), I like to use an anecdote when I do this:
A friend of mine claimed that he was able to lose weight because he started drinking coconut water. If you wanted to test if coconut water really caused weight loss…
What would be your independent variable? (coconut water)
What would be the dependent variable? (any change in your friend’s weight)
Then I explain that while he was drinking coconut water every day, he also began riding his bicycle with his wife every day. I’ll ask students what the problem with his experiment was… hopefully they come up with the fact that he had introduced a second variable (the bike riding) and that everything but the independent variable should remain constant.
I then move to the next slide (11) which introduces the idea of splitting your experiment into groups, the control group and the experimental group.
Finally, I’ll ask the students, “OK… so what if my friend and his wife both ride bikes so that is a constant, but only he drinks the coconut water…”
Who would be the experimental group? (your friend)
Who would be the control group? (your friend’s wife)
I’ll then double check with a question of why there is a control group (to be used for comparison with the experimental group).
When we arrive at the section discussing the difference between qualitative and quantitative data (slide 12), there are two slides: one with a picture of a group of birds (slide 13) and the other with two different snakes (slide 14).
For the picture of the birds I ask students to take 1 minute with their partner and write down as many quantitative and qualitative observations as possible. Then I randomly ask groups to share some observations in each category. I may also make my own observation and ask if it is a qualitative or quantitative observation. This serves to reinforce the distinction between the two types of data, which can be especially confusing for some students because of the similarities in the two words. (This can offer another opportunity to look at prefixes as in the etymology lesson, quanti- referring to numbers, and quali- referring to qualities or characteristics)
For the second picture, we repeat the same process. However, I ask students to focus on distinctions between the two snakes. I then explain that this is an example of mimicry, where the harmless king snake mimics the venomous coral snake. I mention the mnemonic, "Red on black, friend of Jack... Red on yellow, kill a fellow." This builds upon the activity in the previous lesson and underscores the importance of recording detailed observations when collecting data. Such distinctions sometimes literally represent the difference between life and death.
For the slide that shows what looks like a marine biologists working on a boat (slide 15), I ask my students why it’s important to collect data during the experiment. Hopefully they understand that,
1. you can’t just rely on memory when collecting data
2. the significance of data collected at a certain point may become more apparent when looking at all of the data and trying to understand trends or patterns
Form a Conclusion:
This section is fairly straightforward, I would just check that students understand:
1. conclusions must be based on the evidence (data) collected during the experiment.
2. scientists don’t win some “best hypothesis” prize for proving their hypothesis correct: discovering that your hypothesis was incorrect is actually more likely to lead to new discoveries and new understandings.
3. graphs are useful because they are a way to visualize quantitative data, making it easier to interpret.
In this section I would just check to make sure that students understand that publication has two main benefits/purposes:
1. to share knowledge so that scientific research can continue to produce scientific knowledge
2. to allow the methods and conclusions of an experiment to be checked by other scientists to verify the results and either agree or disagree with the conclusions, in turn either challenging or lending support to a hypothesis.
To check for understanding here, I might return to the anecdote of my friend’s miraculous weight loss. I’ll explain that, in a sense, he “published” his experiment by telling it to me. We can then go over the flaws in his experiment that were apparent and what could have been changed to make sure that the coconut water was as important as he believed.
Again, in the interest of time when checking for understanding, it may be useful to present some of these points directly, but it is always better if the students themselves can generate these understandings.
As a very short wrap up, I would simply review the steps of the scientific method with some descriptions of scientists at work.
For example, "If a scientist thinks that orange juice cures colds quickly, they are doing what?" (stating a hypothesis) "How would they test their hypothesis?" (conduct an experiment). "Ok, what would the independent variable be?" (the orange juice), "and the dependent variable?" (how long it take for them to get better), etc.
Often enough, students will bring up teachable moments in their responses that allow you to review the content of the lesson.
Some other review type questions:
a scientist thinks...
- Mice prefer cheese more than other foods
- Hot weather ripens fruit
- Fingerprint patterns determine intelligence
- Vinegar helps plants grow
- Classical music helps students prepare for tests
Etc... Feel free to think up your own scenarios and try as many of these as you can to review the content of the lesson. Students will have more extensive practice with experimental design in the next lesson.