Division: Two-Digit Divisors, Part 2

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Objective

SWBAT apply the steps of the division algorithm to find the quotient of a three-digit dividend and a two-digit divisor and use estimation to gauge the reasonableness of the quotient.

Big Idea

The division algorithm is an efficient way to determine a quotient given any division context.

Think About It

7 minutes

Students work in pairs on the Think About It problem.  

This lesson allows students to get more practice with what they learned in the previous lesson,   applying the division algorithm to real-world problems.  In this lesson there are new variations:  the area problems, and larger dividends.  Long division, with multi-digit divisors, can be difficult for students and I've allowed time in my unit for students to get additional practice.  

Guided Practice

10 minutes

I work with students on the Guided Practice problem set.  All work on these problems includes annotation, a model, an estimate, the division work, repeated addition as needed, a multiplication check, and a full sentence answer.  I explain more about the implementation of this section in the video below.

 

Partner Practice

20 minutes

Students work in pairs on the Partner Practice problem set.  As students are working, I am circulating and checking in with each group.  I am looking for:

  • Are students explaining their thinking to their partner using the language of place value?
  • Are students drawing a bar model?
  • Are students using estimation to help them divide?
  • Are students using multiplication to check their work?
  • Are students responding in a full sentence?

 I am asking:

  • Explain you determined this answer. 
  • Tell me about your model.
  • What strategy did you use?
  • How did you use estimation to help you divide?
  • How did repeated addition help you to find your quotient?
  • How did you check your work? 

After 15 minutes of partner work time, I have one student share his/her work with the class for Problem 2.  The class then claps out their answer for the place value portion of the question. 

 

Independent Practice

15 minutes

Students work on the Independent Practice problem set.  As students are working, I am looking to be sure that their work space has all of the components I expect them to have.  All of the pieces mean that students are not working through a large number of problems during work time, but they are spending valuable time making sense of the problems.

As students are working, I display the Criteria for Success for this problem set, so that students can self-monitor and make sure they're including everything expected in top quality work:

  • Annotations
  • Bar model
  • Estimate
  • Standard algorithm
  • Repeated addition
  • Check
  • Full sentence

Closing and Exit Ticket

8 minutes

After independent work time, I have students turn and talk with their partners about Problem_3. I expect that some of my students may have been thrown by the fact that there was no remainder, so there are 14 in the last stack. After their conversations, I plan to ask students why we wouldn't say there were 0 in the last stack, because there was no remainder.  I want my students to practice interpreting the quotient and remainder, based on the context of the problem, in an important instance like this one.

Students then work independently on the Exit Ticket to close the lesson.  A sample is included here.