Lesson: Divide Decimals by Decimals

Teacher:

Subject:                                                                           

Kurt Sarsfield

5th Grade Math Problem Solving

Date: March 11, 2010

Lesson

Divide Decimals by Decimals to the Thousandths

SWBAT divide decimals by decimals.

Vocabulary:

For review: quotient, divisor, dividend

Agenda

Power Up

Brain Bucket 

Synapse Stretch

Notes with Picture It

CW—What’s Your Level

Exit Ticket and Check

Introduction to Lesson/Hook

Synapse stretch.  Independent in Harvard and McGill.  Guided in Augsburg and Michigan.

Picture It

What is 0.6 divided into groups of 0.2?

Read the question on the Picture It.

How would I write this word sentence as a number sentence?

Let’s think about what this means.

What amount is the total I am dividing up? (Rephrase if necessary…What amount am I starting with?) 

How much will be in each group?

So I am putting 0.6 into groups of 0.2.

How much is going to be in each group?

In my visual, how would I shade 0.6?

Now, I am going to make groups using circles.

What do I need to circle to make groups of 0.2? (two pieces)

If I continue to circle groups of two tenths, how many groups will I have?

Did you notice anything about this problem? (too open-ended for lower classes)

I noticed something. What is the quotient of 6 divided by 2?

Example 1

5.25 ÷ 0.5

First, set up your division problem in the house.

This is different than what you did in Ms. Falbo’s class because the divisor has a decimal point.

To begin the problem, move the decimal point over one place in the dividend and the divisor.

Now, start by bringing up your decimal point to the quotient. 

Now, I am ready to divide.

How many groups of 5 can I make with 5?

Write a 1 above the 5. Multiply, subtract and which digit do I bring down?

Continue questioning through division.

Example 2

0.468 ÷ 0.4

When I have a decimal in my divisor, what can I do so that there is no longer a decimal in my divisor?

After I move the decimal but before I divide, what do I need to write in my quotient?

Question through division steps.

Closure: 

Check the exit ticket.  Students will check super hero if the question was right, sidekick if they got the correct digits but made an error with the decimal, and apprentice if they did not get the correct answer on this question.