Teacher Notes
X
Build a stack of seven connecting cubes and a stack of nine
connecting cubes to display for students. Read and discuss each
question. Emphasize that 9 is two more than 7 and 7 is two less
than 9. Point out that if you add two cubes to seven cubes, there
will be nine cubes, and if you take away two cubes from nine
cubes, there will be seven cubes. Encourage students to use their
desk number lines to model two more and two less.
Repeat with one or two other combinations where one stack
has two more cubes than the other.
K. Two More and Two Less 
Here is a stack of seven cubes. Here is another stack of nine cubes.
- How many cubes should we add to the stack of seven cubes
to make both stacks the same?
- How many cubes should we take away from the stack of nine
cubes to make both stacks the same?
