# Dividing by 2-Digit Numbers (Day 2)

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## Objective

Students will be able to use expanded form of numbers in dividing two-digit numbers, to better understand division and how it works.

#### Big Idea

The "standard algorithm" uses the expanded form of numbers!

## Language Objective and Prior Knowledge

Language Objective: Students will use academic language when explaining their thinking center on division. Examples: divisor, dividend, quotient, and remainder.

Prior Knowledge: Multiplication facts, basic division skills, rounding and estimation.

## Math Blast - Lesson Activator

15 minutes

MathBlast 23 Number of the Day

Math Blast is a quick, fun, fast-paced math game! Every day starts with a Number of the Day. This is the tool I use to not only recall, reteach and pre-teach but it is my way to start classroom management. Students know the expectations of how to come in and get right to work. I do not have to spend any time waiting for students to get ready. Class starts immediately. And since I include music students are really engaged. I also encourage students to support each other for those struggling learners. This is also a great vehicle to expose students to concepts that I know will show up in state testing so that when we do get to these lessons students have already seen the work. Math Blast’s progression goes from easy to hard on the difficulty scale!

Students use a white board and divide it up as follows:

 This space students write in the number of the day. This section is the factors of the number of the day. This section the students put the number of the day over 100. This section students write if the number is Prime, Composite or Square. Using the fraction, students write it as a decimal and a percentage. This section the students put the above fraction in Lowest Terms if possible.

## See, Think, Wonder

5 minutes

Andy Warhol's Cow

I end Math Blast and lead into my lesson with a See, Think, Wonder. The art is choose always relates to the unit I am teaching. It is a real fun way to get your students to think deeper about a subject without them knowing that they are doing it.

The SEE part is pretty basic thinking, I see….

The THINK part gets them thinking a little deeper. This art makes me think about….

And the WONDER gets them really thinking deeper. This art makes me wonder if….

It is my way to getting their brains ready to think about math and I find that the transition is great. It is also a quick chance to expose my students to different types of art.

Note: You don’t have to use art; I use art because I am passionate about art. Use examples of things that ignite your passion!

## The Elevator Speech

10 minutes

Concept: Students will be using different methods for dividing, using rounding and estimation and then long division ( 3 digit x 2 digit).

Yesterday we discovered something pretty cool about doing long division, what did we learn?

In solving for the answer, if we round and estimate first we can be more accurate in long division.

So today we’re going to take all of that good thinking and put it to practice. SO WHO’S READY?! (I like to get them hyped up when doing division, most of the students that come to my room are convinced that they can’t do long division but they leave knowing! You just have to change their mind set on this.)

We are going to use rounding and estimating again because, it’s not just for small numbers, which is awesome.

Let’s look at 421 ÷ 60.

We can round that to be.....(can invite student response) 420 ÷ 60.

Can we simply that? (42 ÷ 6) which is....(can invite student response) 7.

Since 420 ÷ 60 equals 7, I am going to start with 70. Using long-division (writing and solving on board) and we’ll end up with 70 with a reminder of 1.

You might want to do another problem before students try it on their own, with a focus on walking them through it to get the rounding part.

I suggest using 332, have students round it to the 10s place (which is 320), now ask them to divide 320 ÷ 80 (4), now have students divide 332 ÷ 80 (4 with a reminder of 12).

## Work It Out

40 minutes

For independent work, use these five problems, pulling your struggling learners into small groups and giving your fast learners 4-digit by 2-digit problems.

129 ÷ 20

461 ÷ 50

321 ÷ 25

301 ÷ 15

222 ÷ 70

## Closing The Deal

10 minutes

I am sure that you are going to have some strugglers here, bring everyone together and talk about not giving up, pushing through and NOT letting Math Beat You! Talk about some great work that you saw happening, ask them if there had any little successes.

The Closing It section of the lesson is very important. This opportunity allows you to bring the class back together and have them make the connection to the learning objective of the day. You should also make sure that you make a connection to the word of the day. This closing gives students the opportunity to make the connection to the launch and they work that they did. It is also another chance to give a quick formative assessment to check for understanding.

## Quick Assessment

5 minutes

The Post-It Poster: Round, estimate, and use long division to solve 120  ÷ 11.

(110 ÷ 11 = 10, 120 ÷ 11 = 10 reminder 10)

This assessment will help you determine if you’ll need more than three days practicing this approach to division. If so, take the extra day and build students' confidence!

The Quick Assessment is supposed to be fast and on the "easy to medium difficulty" level. You are checking to see if students understand the basic concept of the lesson. If you make the problem difficult you are adding a different level of assessment. If you are teaching a higher level class adding a difficult layer might be appropriate but please note that I do not find it necessary to add this level.