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T267 Lesson Plan
October 28, 1996
Topic: Multiplication of fractions
Grade Level: 5th grade
Students will able to:
l) solve simple multiplication fraction problems using manipulatives.
2) verbalize that when multiplying fractions less than one the result will be less than the factors.
Materials: Overhead projector large overhead geoboard for demonstration overhead transparency of worksheet problems (Exploring multiplication of fractions)
Overhead transparency of geoboard recording paper ( Reys pg. 357.)
For each group of two students: colored pencils or markers of two different colors ruler
geoboard recording paper (Reys pg. 357) – attached geoboard and rubber bands
for each student:
Worksheet – Exploring Multiplication of Fractions (attached)
A) Anticipatory set (10 minutes)
Students will work in pairs to solve this problem. One student will manipulate the geoboard and the other will draw the results on the geoboard recording paper.
Problem: Mr. McGregor has a garden that is a rectangle 3 units by 2 units. He wants to plant flowers on half of the garden Show how he would divide his garden on the geoboard. Then draw it on the paper and shade in the part that would be flowers with one of the colors. Ask the students:
How much of the garden will be flowers? How much is 1/2 of a whole?
Is the result more or less than the whole? Demonstrate the above on the overhead geoboard and geoboard paper transparency.
B) Concept Development (30 minutes)
Continue to work in pairs. Switch tasks.
1.) Now Mr. McGregor decides that 1/3 of the flowers in the garden should be daisies. Show what part of the total garden will be daisies on your geoboard and draw it on the geoboard paper. Color the part of the garden that will be daisies another color. Ask the students:
How much of the entire garden do the daisies cover?
How much is 1/3 of 1/2?
Is the result greater than or less than our two factors 1/3 and 1/2?
Demonstrate the above on the overhead geoboard and geoboard paper transparency.
2.) Have the students solve the following problem: Suppose you get 1/2 of a rectangular cake of any size. You eat 3/4 of that half. Predict whether the amount that you eat of the entire cake will be greater than or less than our factors of 1/2 and 3/4. Make a drawing to show what part of the whole cake you ate. Ask the students:
How much of the cake did you eat?
How much is 3/4 of 1/2?
Is the answer larger or smaller than our factors of 1/2 and 3/4?
Demonstrate the above on the overhead geoboard and the geoboard paper transparency.
C) Practice (30 minutes) Have students work individually on the problem worksheet Exploring Multiplication of Fractions. They may use the geoboards first if they wish.
D) Closure (20 minutes) Discuss what the students found on the worksheet. Ask students to come up and demonstrate how he/she solved each problem on the overhead projector using the Exploring Multiplication of Fractions transparency.
Observe students as they work with geoboards, geoboard recording paper, and worksheets. Collect and evaluate each student’s worksheet.
*Cramer, K. & Bezuk, N. (1991). Multiplication of fractions: Teaching for
understanding. Arithmetic Teacher. 39, 34 – 37.
*Ginsburg, H.P. et al. (1992.) Mathematics – 5th grade edition. Silver Burdett & Ginn, Morristown, NJ, 352 – 355.
Ott, J.M. (1990). A unified approach to multiplying fractions. Arith metic Teacher. 37, 47 – 49.
*Sinicrope, R. & Mick, H.W. (1992.) Multiplication of fractions through paper folding. Arithmetic Teacher. 40, 116 – 121.
Sweetland, R.D. (1984.) Understanding multiplication of fractions. Arithmetic Teacher. 32, 48 – 52.