## Reflection: Rigor Estimating Addition and Subtraction of Mixed Numbers - Section 3: Guided Practice

Estimation is a concept that I spend a great deal of time working with my students on.  I consistently emphasize that estimations are supposed to be almost automatic and flexible.  I discourage students from answering estimation questions by solving for the exact answer and then rounding that answer, a strategy that some students rely on.

It is my goal to teach students to use estimation to help them judge their answers for reasonableness of their answers, or to make mathematical choices based on reasonable estimates.

At the same time, students need to be able to understand how others make estimates too.  Understanding the reasoning of others is also essential part of mathematical proficiency.  To help students think about estimation, consider others' estimates, and determine (from a set of choices) the best estimate, students are challenged to take on the role of a "test maker".

I provide student's with the question.  "What is the best estimate for this problem?".

They will determine the question, write 4 choices to be used as answers.

Determine the choice that represents the best estimate and then write about why.

Students are encouraged persuade me that they have chosen the best estimate by including an explanation of why the others are not the best in their answer.

This lesson is rigorous because it requires students to generate their own problems as well as possible choices, it is open-ended, and also requires students to draw from knowledge of writing to persuade.  They consider the strategies they have learned to persuade, the topic, audience, and purpose to write an informative, paragraph to justify their choices.

Establishing a purpose
Rigor: Establishing a purpose

# Estimating Addition and Subtraction of Mixed Numbers

Unit 3: Adding and Subtracting Mixed Numbers
Lesson 10 of 11

## Big Idea: Students become "test makers" today as they write multiple choice questions and possible choices for finding the BEST estimate.

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Standards:
Subject(s):
Math, Number Sense and Operations, Fractions, estimate, mixed numbers, estimate (sums and differences)
45 minutes

### Julie Kelley

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