Oh yes, I wrote about motivation. I explained why and gave an example about it. But I just wrote one point. I haven't had any idea to write more.It's hard to know. You could talk about one point and go into some depth. You could also talk about some related topics.
300 words is not too long.
So what are you going to write about?
I think motivation plays an important part as to whether a student works harder or not. What do you think?