standard_description: Graph the solutions to a linear inequality in two variables as a half plane (excluding the boundary in the case of a strict inequality), and graph the solution set to a system of linear inequalities in two variables as the intersection of the corresponding half-planes.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for making a ten when adding within 20. The numbers chosen lend themselves to making a ten to find the value of the sum. These understandings help students develop fluency and will be helpful later in this lesson when students make a ten when adding one-digit numbers and two-digit numbers.
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 methods.
Keep expressions and work displayed.
Repeat with each expression.
Student Facing
Find the value of each expression mentally.
\(8 + 2\)
\(8 + 5\)
\(9 + 8\)
\(7 + 6\)
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Activity Synthesis
“How could
\(8 + 2\)
help you to find the value of
\(8 + 5\)
?” (I can add 2 to 8 to get to 10, and then I have 3 more to add.
\(10 + 3\)
is 13.)


aligns: no