standard_description: Use variables to represent two quantities in a real-world problem that change in relationship to one another; write an equation to express one quantity, thought of as the dependent variable, in terms of the other quantity, thought of as the independent variable. Analyze the relationship between the dependent and independent variables using graphs and tables, and relate these to the equation. For example, in a problem involving motion at constant speed, list and graph ordered pairs of distances and times, and write the equation d = 65t to represent the relationship between distance and time.
problem_activity: Warm-up
The purpose of this warm-up is to reactivate students’ understanding of tape diagrams to make it more likely that tape diagrams are accessible as a tool for them to choose in this lesson. The diagram was deliberately constructed to encourage some students to write an equation like
\(24=3(a+2)\)
and others like
\(24=3a+6\)
. Monitor for one student who writes each type of equation.
Launch
Arrange students in groups of 2. Give 5 minutes of quiet think time and time to share their work with a partner followed by a whole-class discussion.
Student Facing
[IMG]
Write a story that could be represented by this tape diagram.
Write an equation that could be represented by this tape diagram.
Student Response
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Activity Synthesis
After students have had a chance to share their work with their partner, select a few students to share their stories. Then, select one student to share each type of equation and explain its structure:
\(3(a+2)=24\)
and
\(3a+6=24\)
.


aligns: no