Converting Fractions into Decimals - GSSD Blogs

Amy Satterfield
Converting Fractions to Decimals Using Base Ten Blocks – Grade 5
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Learning Objective
Students will convert fractions into decimals by dividing the numerator by the denominator with
the use of base ten blocks.
Common Core Standards
Standards for Mathematical Content
CCSS.Math.Content.5.NF.B.3 Interpret
a fraction as division of the numerator
by the denominator (a/b = a ÷ b)
ex. by using visual fraction models or
equations to represent the problem.
Prior Knowledge
Standards for Mathematical Practice
• Make sense of problems and
persevere in solving them.
• Construct viable arguments and
critique the reasoning of others.
• Model with mathematics.
• Use appropriate tools strategically.
• Attend to precision.
Materials
• Definitions of the terms numerator
and denominator
• Decimal place value
• Division
• Base ten blocks for each pair of
students
• Smartboard with virtual base ten
blocks
• Assessment question page
Procedure
Pre-assessment: Have students share what they know about fractions and decimals orally, as a
class.
Introduction: Explain to students that we can represent numbers several different ways. We can
represent the same amount as either a decimal or a fraction. Today we are going to be
working on converting fractions into decimals.
Modeling: “Let’s start with a fraction many of you might already know the decimal equivalent
of. Your friend is coming over after school. There is only one cookie left, so you decide to
share the cookie equally. This hundreds block represents the one cookie. We need to divide
the hundreds block equally in half. To do that, I am going to exchange my hundreds block
for 10 ten rods. Each ten rod represents one-tenth. Now I need to divide these equally into
two groups. When I have divided the pieces equally, I have five ten rods in each group,
which is five-tenths.” (Use the Smartboard to show exchanging the hundreds block for 10
ten rods. Then separate the ten rods equally, one at a time, ending with five in each group.
Write 0.5 on the Smartboard.)

Guided Practice: Next, the students and I will work on solving problems together. The students
will be working in partners and using the base ten blocks.
Problem: You are making a project in art class. There are two pieces of paper, but five
students need to use a part of the paper. You need to share the papers equally. What decimal
represents how much of the paper each student gets?
Show two hundreds blocks on the Smartboard. Trade those hundreds blocks in for 20 ten
rods. Have students work with their partner to separate the ten rods into five groups. Walk
around to check students’ work and assist when necessary. After giving students a chance to
figure it out for themselves, work the problem out on the board using the base ten blocks.
Then, record the answer as 0.20 on the Smartboard.
Next problem: You decided to invite three friends over this weekend, so there are four of
you total. You only have one large bottle of soda to share. What decimal represents how
much of the bottle of soda you each get?
Show one hundreds block to represent the one bottle of soda. Trade that hundreds block in
for 10 ten rods. Have students work with their partner to separate the ten rods into four
groups. Walk around to check students’ work and assist when necessary. After separating
the ten rods equally, 2 ten rods should be left over. Ask students how many ten rods are in
each group. Record 0.2 on the Smartboard.
Explain to students that we have 2 ten rods leftover. We need to exchange those for 20 ones
cubes so that we can divide them equally. Have students divide the ones cubes equally
among the four groups. Walk around to check students’ work and assist when necessary.
Ask students how many ones cubes you added to each group. These represent hundredths.
Add 0.05 to the answer of 0.2 on the Smartboard to make a total of 0.25
Independent Practice: Students will independently solve this problem using base ten blocks:
Your family ordered one large pizza, and there are five people in your family. What decimal
represents how much of the pizza each person gets? Draw a picture of how you divided your
base ten blocks.
Assessment
Next Steps
• Informal observation during
guided practice portion of
lesson
• Check independent practice
question for correct answer
and ability to prove answer
with a drawing
• Convert fractions to decimals
using hundreds grids
• Convert fractions to decimals
using standard long division
algorithm
• Review/Practice with iPad app:
Math Tappers - Equivalents