Using PhET Simulation to Test Sinking and Floating for Solids (Day 1)

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SWBAT collect observations from various density simulations.

Big Idea

Evidence-based explanations derived from evidence-based argumentation can happen only if students collect their own data. This lesson gives students time to manipulate various characteristics of matter to deepen their understanding of density.


This sinking or floating reinforces several aspects of density that I want my students to experience, ponder and use to deepen their understanding, including:

1) Since density is a characteristic property of matter, different types of matter will have different amounts of matter/unit volume, based on their chemical composition (atomic or molecular structure);

2) Matter that has different masses but the same volume will result in different densities;

3) Matter that has different volumes but the same mass will result in different densities;

4) Changing the volume, which results in a proportional increase in mass, results in specific matter retaining its characteristic density. Students still have difficulty accepting this phenomenon, despite experiencing it in this lesson, so it will be good to give them more exposure to this reality.  

5) Sinking or floating of matter is dependent on the density of the liquid that the matter is being placed or poured into. Density in nature results in the occurrence of many phenomena that involve weather, plate tectonics, salad dressings, etc.

Students will use this link to access the simulation.

On day one, I simply facilitate an activity that asks students to experience each of the 5 parts of the simulation, highlighted in the top right corner of simulation. I give them a general structure, which includes creating a separate data table for each of the 5 parts and then recording observations and questions about what they're experiencing. Finding meaning and making connections will occur tomorrow when I encourage students to analyze their results and create evidence-based explanations.  

Introducing Simulation and Expectations for Activity

5 minutes

Educators should familiarize themselves with this simulation, prior to having students use it in class.  The goal of the simulation is for students to make predictions, manipulate aspects within the simulation and then record the results (evidence).

Students Investigate Various Predictions and Record Results

35 minutes

I want my students to first experience the simulations, record observations and ask questions, prior to them analyzing their results. I encourage them to record the information required to calculate density and observe whether the objects float or sink. Additionally, I want students to describe how the cubes are floating. For example, "Wood floats, but only about 1/3 of it is under water." Later, we will come back to this part of the activity to deepen our understanding of density.

Part of students planning and carrying out an investigation is properly setting up a data table, so I ask students to develop one and share their ideas with their group. We then discuss how the table should look and everyone uses that set-up.  

I inform students that for the custom simulation they will need to collect 2-3 samples of the same material. In other words, they will need to manipulate the mass or volume and record that information in their data table.  I demonstrate this on the board and answer any questions.

Rationale: Tomorrow students will calculate the density of different size cubes of the same type of matter and see that density is the same. If they aren't encouraged to manipulate more than one cube then they will not make this connection.

I then show students how to navigate to the next simulation by clicking on the circle next to the name (top right). I quickly activate their prior knowledge about water displacement by asking them how to measure the volume of an object that floats--they have to click on and drag it under the water. They then subtract to find the difference, which is the volume of the cube.  

We then go to the computer lab or use our Chromebooks--this simulation uses HTML5 coding, so it works on Google platforms. 

KLEWS Chart Reflections--What, in general, did we learn?

5 minutes

I certainly don't expect students to have a deep understanding of how density works, but I do want them to reflect on what they Learned and record any questions they have have stewing in their brains in the 'Wonderings' section of their KLEWS chart.  

Responses will vary for each student --that's okay -- kids learn at different rates; NGSS lessons are sometimes messy.  Embrace the process of learning that may be skewed when compared to a traditional science classroom.

Note: Some classes may need more than one day to complete the 5 parts of the simulation.

Tomorrow, students will be given guiding questions that will help drive their analysis of their results and support their claims with evidence-based explanations.