problem of the day problem of the day reasoning length © richard a. medeiros 2005 next 148 -149
TRANSCRIPT
Problem
of the
Day
Problem
of the
Day
Reasoning LengthReasoning Length© Richard A. Medeiros 2005
next 148 -149
Selina must draw a six inch line on the chalkboard, but she has lost her
ruler. The only tools she has are chalk and a sheet of paper. She
knows that this type of paper is 8 ½ inches wide and 11 inches long.
Selina must draw a six inch line on the chalkboard, but she has lost her
ruler. The only tools she has are chalk and a sheet of paper. She
knows that this type of paper is 8 ½ inches wide and 11 inches long.
How can she use the paper to help draw the line she needs?
How can she use the paper to help draw the line she needs?
nextnext
I have to figure out how to draw a six inch line on the board without a
ruler. I can use a piece of paper 8½ x 11 inches and a piece of
chalk. After thinking about my options and testing several ideas, I have decided to place the paper vertically (11inches) on the board
next
Solution
and place a mark at both ends ofthe paper. Then I will move the paper to the right lining it up with my chalk mark and will place another mark on the end. Finally, I will line the paper
up horizontally (8½ inches) at my first mark. Then, I will erase the
11 inches, and 6 inches will remain.
next
Mathematically, my equation would be…
8½ + 8½ - 11= m Logically, my answer makes sense both mathematically and manually.
next
8½ x 11 8½ x 11
8½ + 8½ = 17
17 - 11 = m m = 6
8½ x 116
17 My solution
8½ x 11
nextnext
11
nextnextnextnext
11 - 8½ = 2½
8½ - 2½ = mm = 6
8½ x 11
62½
8 ½ x 11
Student’s solutionnextnextnextnextnext
11 ÷ 2 = 5½
8½ - 5½ = 33 x 2 = m
35½
8½ x 11
Math Coachsolution
m = 6
8 ½ x 11
3nextnextnextnextnextnext