standard_description: Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
problem_activity: Narrative
The purpose of this activity is for students to write a
\(10 + n\)
expression that is equal to a given expression. Each expression given has three addends, two of which make a ten.
Required Materials
Materials to Gather
Connecting cubes or two-color counters
Double 10-frames
Launch
Groups of 2
Give students access to double 10-frames and connecting cubes or two-color counters.
“Now you will write a
\(10 + n\)
expression with the same value as each of the given expressions.”
Activity
5 minutes: independent work time
3 minutes: partner discussion
Student Facing
Write a
\(10 + \boxed{\phantom{3}}\)
expression that has the same value as each expression.
\(5 + 7 + 5\)
\(3 + 7 + 6\)
\(1 + 9 + 9\)
\(4 + 8 + 6\)
\(8 + 10 + 2\)
If you have time, write as many expressions as you can with 3 numbers that are equal to
\(10 + 5\)
.
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
Display each
\(10 + n\)
expression.
“In order to make adding three numbers easier, we can rewrite each expression as a
\(10 + \boxed{\phantom{3}}\)
expression.”
Invite students to say the value of each
\(10 + n\)
expression together.


aligns: yes