Warm-Up

Exam 3 #11

Give two reasons why Vance’s reasoning is wrong

Hint: Compare to a landmark and use equivalent fractions.

Student Errors• 7/8 + 3/32 + 1/16 is less than 1

because 7/8 is almost 1, and 1/16 is about 0, and 3/32 is about 0, so almost 1 + 0 + 0 is less than 1.

Student Errors• 8 3/4 • 2 7/8 • Find a common denominator:• 8 6/8 • 2 7/8 = 16 42/64 which is

simplified to 16 21/32.

Student Error• 4 7/8 ÷ 8 7/8 = (4 ÷ 8) ÷ (7/8 ÷ 7/8) =

1/2 ÷ 1 = 1/2

Student Error• 25 - 1/2 = • 25

- 1/2 25 1/2

Student Error• 29 1/7 - 16 4/7• 29 1/7 = 28 11/7

- 16 4/7 = 16 4/7 12 7/7 = 13.