Students will model comparison subtraction contexts involving positive and negative integers and solve. 

In this task, students will leverage the subtraction structure of comparison. They will explore the context of comparing floors in an apartment building. Students will use a number line to compare the magnitude between two floors, represented by integers. Some of the big ideas revealed in today’s lesson include:  

• Situations involving addition and subtraction can be modelled using a number line;
• Integers include zero,  all whole numbers and their opposites;
• Integers represented on a number line show their relative distance from zero;
• An integer can represent a change or a quantity;
• Two integers can be represented as positions on a number line to determine the distance between them (magnitude); 
• The order in which a subtraction statement is written is important.

Show students the following video:

Then, ask students:

What do you notice?
What do you wonder?

Give students 60 seconds (or more) to do a rapid write on a piece of paper.

Then, ask students to share with their neighbours for another 60 seconds.

Finally, allow students to share with the entire group.

Some of the noticing and wondering that came up in a class recently included:

• I notice a building. 
• I notice there are floors below the ground. 
• I notice cars parked on different floors below ground.
• I notice people on different floors.
• I wonder which car belongs to whom?
• I wonder if that is an elevator in the middle? 
• I wonder how long the elevator takes to get to the person’s car. 

At this point, you can answer any notices and wonders that you can cross off the list right away. Confirm for students that this building is in fact an apartment building with underground parking for the residents. The person lives on the 18th floor and their reserved parking spot is on the third floor below ground level.

Since you have already taken some time to set the context for this problem and student curiosity is already sparked, we have them in a perfect spot to help push their thinking further and fuel sense making.

Share the following prompt.

Next, share the following visual prompt briefly and ask the following question:

How many floors does the person need to travel by elevator from their car to their apartment? Use a model to justify your answer. Write an equation to represent this scenario.  

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Login/Join to access the entire Teacher Guide, downloadable slide decks and printable handouts for this lesson and all problem based units.

Login/Join to access the entire Teacher Guide, downloadable slide decks and printable handouts for this lesson and all problem based units.

Login/Join to access the entire Teacher Guide, downloadable slide decks and printable handouts for this lesson and all problem based units.

Show students the following reveal video:

Provide students an opportunity to reflect on their learning by offering these consolidation prompts to be completed independently.

Consolidation Prompt #1:

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Consolidation Prompt #2:

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We suggest collecting this reflection as an additional opportunity to engage in the formative assessment process to inform next steps for individual students as well as how the whole class will proceed.

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