standard_description: Recognize that sequences are functions, sometimes defined recursively, whose domain is a subset of the integers. For example, the Fibonacci sequence is defined recursively by f(0) = f(1) = 1, f(n+1) = f(n) + f(n-1) for n ³ 1.
problem_activity: Narrative
The purpose of this Number Talk is to elicit strategies and understandings students have for making a ten to add. When students look for ways to decompose an addend to make 10, students look for and make use of the structure of numbers and the properties of operations (MP7). These understandings help students develop fluency and will be helpful later in this lesson when students will need to be able to add within 20.
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 sum mentally.
\(8 + 2\)
\(8 + 3\)
\(8 + 5\)
\(7 + 6\)
Student Response
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Activity Synthesis
“How does making 10 help in finding the value of the sums?” (It helped me because I was able to use facts I already know. I know
\(7 + 3 = 10\)
and I know
\(10 + 3 = 13\)
.)


aligns: no