Thanks a lot my dear friend Tobi. I taught it to grade 9 students for 7 years and found that 80% of the kids struggle in recognizing the formula of the substance and what to change and what not to change, how to count the number of atoms on both sides of the equation.
Based on that assessment I prepared my lesson plans. It's one size fits all and I try to make the size which at least fit the most of my students. LOL..