Reflection: Student Feedback Standard Algorithm Book - Section 3: Student Practice


After collecting student work from this lesson, I noticed that half my students were quite successful at solving 2-digit x 2 digit multiplication problems using the standard algorithm. Here's an example of a Proficient student. 

The other half of my students were able to correclty complete the majority of the problems correctly, but got four to nine problems wrong. This showed me that these students were Nearing Proficient as they were able to complete many problems correctly, but needed further support with achieving correct answers on all the problems. In order to identify common mistakes and misconceptions, I took the time to analyze student work carefully. Interestingly, I found a wide range of mistakes:

Forgetting to Add up Partial Products

Several students forgot the last step... adding the partial products! Following multiple steps can be difficult! 


Forgetting to Multiply by Each Digit

Here, the student forgot to multiply 5 x 0 to get a bottom partial product of 4500. 


Adding a Carried 1 instead of a Carried 2

This student multiplied 7 x 3 to get 21, carried the 2 in her head, then multiplied 7 x 1 to get 8. Instead of adding 2, she added the previously carried 1.


Adding Instead of Multiplying

This student added 7 + 3 + 1 instead of justing multiplying 7 x 3 to get 21 (the 1 shouldn't have been carried). 


Multiplying by the Carried Digit (8 x 4)

This student multiplied 8 x the carried 4 (from 8 x 4 = 40) instead of 8 x 3. 


Not Lining up Digits to Add

This is a simple, but common mistake. You'll see that the ones in the first partial product is lined up with the tens in the second partial product.


Incorrectly Adding Partial Products

This student simply added 7 + 0 incorrectly. 


Knowing Multiplication Facts

This student multiplied 5 x 9 to get 40 instead of 45.


Tomorrow, I will conference individually with each of these students to help them identify the common mistakes they are making.  

  Student Feedback: Common Mistakes
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Standard Algorithm Book

Unit 12: Multiplication: Double-Digit x Double-Digit
Lesson 3 of 7

Objective: SWBAT multiply a 2-digit number by a 2-digit number using the standard algorithm method.

Big Idea: Students will create a book to model the steps of the standard algorithm.

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  100 minutes
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