Dealing with Decimal Models

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Objective

SWBAT model decimals using decimal grids, base 10 blocks, and number lines.

Big Idea

Modeling decimals lays down the ground work of learning how to compute and estimate.

DO NOW

10 minutes

The students will be completing several arithmetic problems to warm them up for the day.  It’s important for the students to understand that what we learn in math should stick with us. 

Tools:  Modeling decimals power point and notes

Decimal Grids

15 minutes

Students will be learning how to model decimals using the grids.  Decimals will range from under 1 to greater than one.  Using the decimal grid helps students visualize what the decimal looks like and sounds like.  This first section has them shading in the appropriate decimal and then reading the grid to write the appropriate decimal.  For each problem, I’m going to use a think-pair-share to help them get started on the modeling. (SMP 1, 3,4 and 6)

Tools:  Modeling decimals power point and notes, extra 10 x 10 grid paper

Base 10 blocks

15 minutes

I like using the base 10 blocks because the students can actually manipulate the tools (SMP 5).  I will be giving them examples that are less than one and greater than one.  I will be using the think-pair-share model here too.  It’s important for students to know they are on the right track. (SMP 3)

Before moving on to the next section, ask the students these two questions to check for understanding.

  1. Three-tenths is equivalent to how many hundredths.  You may have to address the word equivalent so that all students know what it means.
  2. How many tenths are the same as ninety hundredths?

I will have the students using the white boards so that I can quickly assess who is getting it and who is not. 

Students have a difficult time making the connection between equivalent decimals.  Have students model what they know and then match the model by using a second set of manipulatives.  For example, if they put down 3 sticks (tenths), ask them what other model from the base 10 blocks could they use to make an equivalent decimal?  The only tool available would be the hundredths.  Ask, "how many hundredths will be needed to make it equal.?"

Tools:  Modeling decimals power point and notes, base 10 blocks

Money

15 minutes

Money is the easiest decimal to model because it is an everyday thing.  Students will be given pictures of the money and have to write the decimal or they will be given the decimal and they have to make it into money.  The students will benefit from a think-pair-share because when they have to create the money, students may model it in different ways which will lend itself to some good discussion (SMP 3)

Tools:  Modeling decimals power point and notes, play money

Number line

20 minutes

The number line is the most difficult for students to understand.  We have worked with the number line before with fractions and whole numbers.  A couple of tricks to get the students to see the intervals:  wrap a rectangle around the whole numbers to show the equal parts.  Have the students find the whole number first then find the decimal after.  Students need to know that decimals are fine tuning our number system so the marks in between can be written as decimals.  (SMP 4 and 5)

Again, have the students do a thinkpairshare before beginning the problem.  

Tools:  Modeling decimals power point and notes, extra number lines

 

Closure

10 minutes

The students will be completing an informal assessment for me to look over and check for understanding.  Since understanding what a decimal looks and sounds like is the ground work dealing with decimals, it is important that they understand them conceptually. 

Tools:  exit slip