Multiplication and Division Concepts 177Rigorous Problem Solving with the Concept of
Equal Products 1
Sophia and her Grandmother made holiday cookies. Each
tray had 55 cookies on it. When Grandmother took the fourth
tray out of the oven, Sophia asked, “How many cookies did
we bake?”
Part A
Grandmother said, “We have 4 groups of 55, but let’s half the
groups and double the cookies in each group by putting the
trays in sets of 2.”
Which equation represents the equal products?
o 4 x 55 = 2 x 100
o 4 x 55 = 2 x 55
o 4 x 55 = 4 x 110
o 4 x 55 = 8 x 11
o 4 x 55 = 2 x 110
Part B
Kirk said, “If there were 8 trays of 45 cookies we could
half the trays and double the cookies twice which would
be 2 x 180.” Do you agree or disagree with Kirk?
Justify your answers with equations.
© 2016, Math Intervention: Grades 3–5, Jennifer Taylor-Cox, Routledge