Using PhET Simulation Observations and Data to Find Patterns and Make Evidence-based Arguments About Density (Day 2)

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SWBAT: Analyze the results from each simulation to find patterns and develop evidence-based arguments about the factors that explain why some objects float, while others sink.

Big Idea

Giving students time to analyze data, develop arguments, listen to others' arguments can lead to deeper understanding. Using evidence to support claims is a crucial part of science and is used here to deepen students' understanding of density.


A great explanation of differences between arguments and explanations, garnered from my social media PLN @DrSPruitt, is that arguments (SEPs 7 and 8) are a process of science and explanations are the goal of science.  In other words, teachers should encourage students to form arguments as part of the analysis portion of lessons, subsequently leading to them explaining their summative understanding of how a particular aspect of nature works.  

In this lesson, I supply students with guiding questions for each of the 5 sections of the simulation from our previous class. Students must first calculate the density of each cube, if they weren't able to  perform that task yesterday during class or for HW. Students then have to argue with their peers, using evidence to support what they are claiming. Once consensus has been established through the argumentation process, students can write a C-E-R for each of the 5 simulations. Note: sometimes consensus is not established, mostly due to miscalculations of density, due to students not recording accurate data on day 1.  

If you notice students struggling with starting arguments, you can use this structure:

  1. Each student formulates an argument on their own, supported with their own data
  2. Each student shares their argument and other students can respond, using their own data to support or refute their partners argument.  This often leads to quick consensus, as it is typical for more than one group member to have the same argument.
  3. If students disagree, they must do so professionally and respectfully.  This is about learning, not making people feel inferior!

The rate of completion will vary from class to class, so plan on spending one to two days on this process.  Students will have 5 C-E-Rs, one for each of the 5 parts of the density simulation, guided by questions on this worksheet.

Do Now

5 minutes

I want to get students thinking about what they experienced in the PhET density simulation, so I ask:

"Did all objects float or sink in water?  Explain why you think occurred?" 

This requires students to activate their prior knowledge and experiences from the simulation and helps frame their mind for today's lesson.  Some students may have to refer to their notes in their notebooks, which will help them find the information needed to formulate their explanations using C-E-R.

Analyzing Results and Developing Evidence-based Arguments

40 minutes

Argumentation leads to students' abilities to explain phenomena.  For each of the five parts of the simulations, students must first formulate their own arguments, share them with the group and come to some consensus.  The questions on this sheet help frame their discussions during this process.

Once students have a consensus argument, supported with evidence, they are asked to write a C-E-R for each simulation.