# Multiplication by 2-Digit Numbers (Day 2)

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## Objective

Students Will Be Able To apply there learned knowledge and the rule of multiplying x10s, x100s, x1000s to the standard algorithm of multiplying by two digits.

#### Big Idea

Understanding the standard algorithm of multiplication.

## Language Objective and Prior Knowledge

Language Objective: Students will be able to express their thinking using academic language like ‘product’ and ‘multiplying’ when discussing multiplication.

Prior Knowledge: Basic multiplication facts.

## Math Blast - Lesson Activator

15 minutes

MathBlast 18 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 Statue of Liberty

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: showing why the standard algorithm of multiplication works because 123 x 42, the ‘x 4’ is really x40.

Script, if needed: Start by writing a stacked multiplication problem on the board:

123

X42

Start to write your work under the line but forget to use the 4 as a 40, leaving out the 10s place

246

492

Stop and look puzzled, look at the class and think out loud. It doesn’t look right does it? They should remember from the lesson prior that I forgot to use the 10s place. So suggest an estimation 123 x 40.

Have a student do this math on a white board and report back the answer (you could have a few students do this or have student do this on a calculator)

Then add 246 + 492 which is 738 and 123 x 40 = 4920. Where did we go wrong? This will lead you to a discussion that the ‘4’ is really 40.

## Work It Out

40 minutes

This lesson we are going to have students create posters for a Gallery Walk Work Session

Using The FOUR Square model students will create two problems again. This time the bottom two sections will be covered with paper (you might want to model this to help for understanding) Also give each person a number for their poster.

 Create a 2 digit by 1 digit multiplication problem, round and estimate the answer. Ceate a 2 digit by 2 digit multiplication problem, round and estimate the answer. Now use the standard algorithm for the above problem. Now use the standard algorithm for the above problem.

Students pick two numbers, once everyone has two numbers go to a long hall and have each student put up their work. Students then go around to each their corresponding numbered poster and do the work on a post-it. Post it on the flap. Once they are done they can look under the flap to see if they are correct. If students finish early, give them post-its with new numbers on them to keep them working.

## Closing The Deal

10 minutes

Talk about the importance of understanding place value in numbers.  "Why is it important?"

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 Assessments

5 minutes

The Post-It Poster: 232 x 22

1. Estimate the total
2. Find the answer with the standard algorithm

The Quick Assessment is supposed to be quick 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.