Using Partial Quotients

5 min

Teacher Prep
Setup
Display each problem one at a time for all to see. 1 minute quiet think time followed by a whole-class discussion.

Narrative

The purpose of this Warm-up is to elicit the idea of partial quotients, which will be useful when students learn a new way to record partial quotients in a later activity. While students may notice and wonder many things about these equations, the idea of dividing a number by decomposing the dividend into smaller and more-familiar parts are the important discussion points.

When students articulate what they notice and wonder, they have an opportunity to attend to precision in the language they use to describe what they see (MP6). They might first propose less formal or imprecise language, and then restate their observation with more precise language in order to communicate more clearly.

Launch

Arrange students in groups of 2. Display the problem stem and four equations for all to see. Give students 1 minute of quiet think time and ask them to be prepared to share at least one thing they notice and one thing they wonder about. Give students another minute to discuss their observations and questions.

Representation: Internalize Comprehension. To support working memory, provide students with sticky notes or mini whiteboards.
Supports accessibility for: Memory; Organization

Student Task

Here are Kiran’s calculations for finding 657÷3657 \div 3:

\begin{align} 600 ~\div~ 3 &= 200 \\[2ex] 30 ~\div~ 3 &= \phantom{2}10 \\[2ex] 27 ~\div~ 3 &=\phantom{21}9\\ \overline{\hspace{2mm} 657~\div~ 3} &\overline {\hspace{1mm}= 219 \hspace{2mm}} \end{align}

What do you notice? What do you wonder?

Sample Response

Students may notice:

  • The 657 is divided by 3 in parts. First, 600 is divided by 3, then 30 is divided by 3, and finally 27 is divided by 3.
  • The hundreds are divided first, followed by two divisions involving tens or tens and ones.
  • Each part—600, 30, and 27—can be divided by 3 without a remainder.
  • The quotients from dividing each part are added at the end.

Students may wonder:

  • How did Kiran know how to break up the 657?
  • Can we divide other numbers this way?
  • Do we always need to break up the dividend into 3 parts in order to divide?
  • Why didn’t Kiran decompose the 657 by place value, into 600, 50, and 7?
Activity Synthesis (Teacher Notes)

Ask students to share the things they noticed and wondered. Record and display their responses without editing or commentary. If possible, record the relevant reasoning on or near the equations. Next, ask students, “Is there anything on this list that you are wondering about now?” Encourage students to observe what is on display and to respectfully ask for clarification, point out contradicting information, or voice any disagreement.

If no students mentioned that Kiran did not decompose the 657 strictly by place value, ask students to discuss this idea and whether it would be just as productive to decompose 657 into 600, 50, and 7.

Standards
Building On
  • 4.NBT.6·Find whole-number quotients and remainders with up to four-digit dividends and one-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
  • 4.NBT.B.6·Find whole-number quotients and remainders with up to four-digit dividends and one-digit divisors, using strategies based on place value, the properties of operations, and/or the relationship between multiplication and division. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.
Building Toward
  • 6.EE.A·Apply and extend previous understandings of arithmetic to algebraic expressions.
  • 6.EE.A·Apply and extend previous understandings of arithmetic to algebraic expressions.

15 min

15 min