Equivalent Expressions

Today my class looked at solving equations. I decided that we needed to review solving equations and substitution in order to work through simultaneous equations. However, when we looked at the equation:

7 – 2x = 9

The issue students had with this question was that they wanted to add 7 to balance the equation because they believed that the sign was part of the 7. We had to stop and look at what 7 – 2x meant and how it also meant – 2x+7.

They weren’t convinced initially and they are an excellent class to teach. They share their ideas continuously and aren’t afraid of getting things wrong. I felt like each time I uncovered an issue, I was faced with another. We spent time looking at equivalent calculations than solving equations.

The class are in year 10 and they are a set 2 of 4, yet they seemed surprised that – 4 + 5 = 5 – 4

So for the next lesson we will be looking at the following questions