Silly Sally Error Analysis
Name:_________________
Sally is a silly little girl that makes silly mistakes!  CHOOSE ANY 5 PROBLEMS BELOW. Analyze her work
in Column #1, and circle her mistake. In Column #2, explain what she did wrong. In Column #3, show
how Silly Sally should work out the problem.
Silly Sally’s Work
(Circle her mistake):
Problem:
Sally’s Model:
-8 + (-3)
- - - - - - - - - -
What did Silly Sally do
wrong?
Show Silly Sally how it’s done!
(Use the same METHOD she used,
but do it correctly!)
Sally’s Answer = -5
Problem:
Sally’s Model:
-4 + (-3) + 2 - - - - - - ++
Sally’s Answer= 5
Sally’s Model of 3 + (-1)
Sally’s Answer: 3 + (-1) = 4
Question: What problem does this
number line represent?
Sally’s Answer: -5 + (-3)= 2
Problem: Rosie owes her friend $10,
but she just found $3. Write and
solve a problem to represent this
situation and how much she now
has.
Sally’s Answer: $10 + $3 = $13
Rosie has $13.
Problem: -2.5 + 10 + (-7.8)
Sally’s Work with
The Algorithm:
7.5 + (-7.8)
-15.3
** Choose ONE Extension Problem, and complete it on the back of this sheet. **
Extension A: Create a Bridge Map with the three methods to solving a problem involving addition of rational
numbers. Use one problem, and show how to solve that problem with each solution method.
Extension B: Create a Double Bubble Map to compare/contrast addition with the same sign vs. different signs.