1. Rob Schupbach Problem #2
CRIN E07: Elementary Math Curriculum and Instruction
Dr. Margie Mason
September 17, 2011
Topic: Computation and Estimation: Factors and Mutliples—Grade 4 (SOL 4.4)
Expected Heuristics: Choose an operation; Make table; Guess & check
Tea with Mr. Tumnus—The Lion, The Witch, and The Wardrobe by C.S. Lewis
Mr. Tumnus told Lucy about a midnight party of fauns and Dryads in the forest of
Narnia. 35 fauns came to the party. There were 3 times as many Dryads as fauns.
How many creatures were at the party?
If the whole group split equally into 5 large circles for dancing, how many were in
each circle?
Answer:
140 creatures at the party and there were 28 dancers in each circle.
Complete Solutions:
For students who are not used to bar diagrams, the natural tendency is to multiply
3 x 35 = 105 creatures at the party. A quickly sketched diagram will show their
error:
There are four units in all, and 4 x 35 = 140. So 140 creatures were at the party.
The second part of the problem is straight-forward. A diagram may not be needed,
but here it is anyway:
140 ÷ 5 = 28. There were 28 dancers in each circle.
Let’s Play Math. (2011). Retrieved September 17, 2011, from
http://letsplaymath.net/
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