Mass vs. Weight: Using Concept Cartoons and Evidence-based Argumentation to Help Deepen Student Understanding

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SWBAT: 1) Define and explain the differences between matter, mass and weight

Big Idea

Students must know what they are measuring before learning how to measure it. This lesson utilizes concept cartoons and evidence-based argumentation to develop students' understanding of mass vs. weight.

Do Now

5 minutes

Students will develop their ability to use evidence to support arguments (SP 7).

Students are usually good about reading numbers off of a triple beam balance, but I often wonder if they actually know what they are measuring.  To get their minds thinking about mass, matter and weight, I like to start out by asking students to complete this do now sheet.

I want to establish a few things in this Do Now:

1) I want kids to think about the words mass and weight by using the question as a formative assessment strategy which they will reflect on later.  Meta-cognitive reflection helps students learn from their previous beliefs.

2) I want to see if they think that mass will change as a result of going to another planet.  FYI: it won't.  Mass is a measure of how much matter something has, so unless parts of the organisms are removed then they will remain the same mass.  Weight, however, will change based on the gravitational pull on a certain planet.  

Note: Muscle atrophy is a challenge for astronauts.  They actually lose weight when they are in space, due to less gravity causing their muscles to weaken and thus losing mass.

Once students have had time to complete this in their notebooks, I ask students to share their thoughts with their small groups and then we discuss as a class.

I take a poll to see how many other students agree with that person's idea.

Using Concept Cartoons to Frame Student Questions and Research

10 minutes

Concept cartoons are an effective strategy for unearthing my students' alternative or pre-conceptions, as well as spark debate among small groups of students and the class.  Concept cartoons can take many forms.  In this lesson I use two images that get to the heart of understanding the difference between mass and weight.  Again, I am trying to establish an understanding of mass before students actually learn how to measure it.  These concepts are covered in later years so I don't want to get into the details too much.  The cartoons serve to distinguish between mass and weight in a student-centered atmosphere, leading to many ideas that will be clarified as students begin to research the topics in a few minutes.

I like to hand out the this worksheet and have students fold them in half and staple in their science notebooks at the conclusion of class.  This keeps pertinent documents with their science notebook entries from class.  Yes, sometimes the notebooks get wide and unwieldy but everything is there for them to view.

Students Investigate Mass and Weight on Different Planets

15 minutes

Students have up to 15 minutes to research the differences between mass and weight, and learn about matter as they choose at least 3 sites from the  List of Acceptable Sites to draw their information from.

It is my objective that students do this research on their own, and I try to limit my role to technology intervention rather than acting as an "information station". If students bring content questions to me, I tend to rephrase the question back to them, and wonder, "Where could I get that information?" By rephrasing I help them to refine their search criteria, while not doing their thinking for them.

Using Evidence From Text and Videos to Support or Refute Our Original Thoughts

15 minutes

I am a firm believer that the skills and strategies learned in ELA, especially as they pertain to using evidence to support claims, should be emphasized in science as well.  Students must be able to use evidence to support their original or altered views and this activity guides students through that process.  

Towards the end of the year, I will not be this supportive when it comes to supplying resources and question prompts.  But this is the beginning of the year and I want to build their confidence so I am walking them through the process of finding evidence, making sense of it, and, ultimately, helping them determine how it supports their original thoughts.

Up until now students have shared their original thoughts on mass and weight, viewed stimulating concept cartoons that evoked thoughts and questions, and researched the topics/questions and recorded their findings in their science notebooks.  It is now time to encourage students to revisit their original thoughts so that they can determine their accuracy using the evidence that they collected.  

Again, I want to support kids on how to do this so I model the process.

I begin by pretending that I thought Buzz was correct--he isn't but I don't tell kids this.  I ask for students to share their thoughts and I model how they should proceed.

Student: "I thought that you would weigh less on the moon because you lose weight the moment you arrive."  Note: MISCONCEPTION ALERT -- astronauts do lose mass when they go to outer space.  You need to state that the astronauts have only been there for a few seconds, how could they lose weight that fast?

Teacher: Okay, so let's look at the evidence that we collected from the texts and videos.  What did we find out that may support that or refute that belief?  Continue modeling so that students can see that the discovery of new evidence can often change our beliefs.

You should then give students the opportunity to revisit the concept cartoon worksheet and ask them to use Claim-Evidence-Reasoning (C-E-R) to state why their original thoughts were accurate or not.

I hand this sheet out to help guide student C-E-R responses. 

Check for Understanding/Student Reflections

5 minutes

You have a few options for Homework, depending on time.

Option 1: Have students finalize their CER write-ups for each picture.


Option 2: Ask students to answer the following question:

"How are mass, matter and weight similar, yet different?"

Option 3: You can assign Your Body in Space: Use It or Lose It reading (NASA) and ask students to summarize it.  You can later discuss how muscle atrophy affects mass in outer space.