Reflection: Connection to Prior Knowledge Adding and Subtracting Mixed Numbers - Section 2: Launch


I know from teaching this is the past, students have a hard time with subtracting mixed numbers.  Prior to this, I have taught those students who struggle to just change the mixed numbers to improper fractions and then subtract, then change them back to mixed numbers. 

This year I choose to try something that gets at the understanding this concept.  I used more modeling, number sense, and connections to prior learning. 

Students regroup when they add and subtract all the time.  Over time, they have moved away from really focusing on the meaning of these procedures and more towards automaticity.  By taking a little time to uncover this prior learning, students are able to connect regrouping fractions into wholes with regrouping ones into tens etc.  

Yes, this is a complex skill because there are many components for solving just one problem, they still need additional practice. But I feel this was a more meaningful approach.  

  Transition student thinking from something old to something new
  Connection to Prior Knowledge: Transition student thinking from something old to something new
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Adding and Subtracting Mixed Numbers

Unit 3: Adding and Subtracting Mixed Numbers
Lesson 8 of 11

Objective: SWBAT solve problems involving the addition and subtraction of mixed numbers.

Big Idea: Regrouping fractions to whole numbers is not unlike regrouping ones to make a 10. Students use rich language as they learn the procedures for adding and subtracting mixed numbers.

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2 teachers like this lesson
Math, modeling, Number Sense and Operations, Fractions, mixed numbers, add and subtract fractions, Critical Area
  55 minutes
screen shot 2014 04 22 at 11 09 10 am
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