If you're talking about the industrial, agricultural, transport revolution etc. You should study it as there is a chance that it will come up in section 5. 3rd year social change comes up in Section 6 every year
Social change as it what you study in third year comes up in question 6 every year on higher level paper! If your higher definitely do it as it is one of the easier long questions worth loads of marks :)
social change in third year is often marked really harshly in question 6 as its the precieved easy question, you will have a choice but if your not good with remembering exact dates then id skip it because one of my teacher told me that they penalize you alot if you don't have the correct dates with social change
Some teachers dont even cover this chapter because students think its easy and attempt it with little study. It is easy to do as it comes up every year but make sure you know the stuff and dont waffle.