Reflection: Developing a Conceptual Understanding Subtracting Across Zeros - Section 2: Introduction to New Material

 

When I have taught subtracting across zeros in the past, I have taught a trick: "borrow from the hundreds, turn the tens and ones place into nines and solve."  In teaching this trick, my students did not develop a conceptual understanding and did not have to understand WHY they were changing the tens place into a 9, etc. 

This year, I modeled subtracting across zeros using place value blocks and I was surprised how many students could clearly explain how to subtract across zeros.  Student accuracy was also higher because students understood the process more deeply.   Allowing students to use place value blocks during their guided and independent practice further helped them develop this conceptual understanding. 

  Don't teach tricks!
  Developing a Conceptual Understanding: Don't teach tricks!
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Subtracting Across Zeros

Unit 6: Three-Digit Addition and Subtraction
Lesson 13 of 13

Objective: SWBAT subtract across zeros (i.e: 100-57=____).

Big Idea: Students use place value blocks to accurately subtract across zeros.

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