standard_description: Prove that, given a system of two equations in two variables, replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions.
problem_activity: Narrative
The purpose of this warm-up is to elicit the idea that fingers and 5-frames both show 10 in 2 groups of 5, which will be useful when students use 5-frames to create a 10-frame and represent quantities on 10-frames in later activities.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Facing
What do you notice?
What do you wonder?
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Student Response
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Activity Synthesis
“How are the fingers and the counters on 5-frames the same?” (Each hand has 5 fingers. Each 5-frame has 5 counters. There are 10 fingers and 10 counters.)


aligns: no