standard_description: Verify experimentally the properties of rotations, reflections, and translations:
- Lines are taken to lines, and line segments to line segments of the same length.
- Angles are taken to angles of the same measure.
- Parallel lines are taken to parallel lines.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for adding on to 10. These understandings help students develop fluency and will be helpful later in this lesson when students write equivalent expressions.
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Activity
Record answers and strategy.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(7 + 10\)
\(7 + 2 + 8\)
\(10 + 9\)
\(4 + 9 + 6\)
Student Response
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Activity Synthesis
“Why did some of the expressions have the same value?”


aligns: no