After a week of looking at formal written methods of subtraction I wanted to see how deep their understanding really was. So using some of the questions from the Maths Hub I posted a few questions onto Seesaw and asked them to record their answers and explanations.
Here is an example from Andrey which shows his understanding of solving addition and subtraction two step problems in contexts, deciding which operations and methods to use and why.
Baimonn explains how to work out the missing numbers in a subtraction sum. This shows a deep understanding of using the inverse relationship between addition and subtraction, and also the column method.
CC explains how to work out a 2 step problem that involves adding and subtracting.
What was great about this activity was it also showed me which children still needed some work on their understanding of a subtraction written method.
Kamilla was so close here. You can hear her brain ticking as she thinks about the first units column, showing her understanding of using inverse and the concept of borrowing.
Using a formal method in her book was not a problem, but being presented with the problem in a different context proved that we need to take another look at applying skills and understanding.
Some confusion between the operations. This also shows me that there is not the depth of number sense that I thought there originally way. Taking another look at place value and using the manipulatives is a must when we review this.
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