Change Sides, Change Signs
The other day, I noticed that my students were struggling with rewriting an equation in Slope-Intercept Form (Solving for y). So I created this desmos activity. CLICK HERE.
One student in particular would always have his signs incorrect. Like every single problem and every single term. I investigated a little bit more and he was using "Change Sides, Change Signs". This 'trick' implies that terms are moving and changing signs. I can see how this might be the case with adding and subtracting terms, but with multiplying and dividing this 'rule' falls apart.
Instead, let's teach our students that the sign isn't changing, the operation is. Not only is it true, it works in every case and in much simpler than a catchy slogan.
This isn't a negative 3 that will turn into a positive 3. Rather, this is minus 3 and we want to do the inverse: add three.