As I work in the schools in Wenatchee, I see, on a regular basis, all kinds of posters in the classrooms. They are designed to encourage the students to be positive and responsible. They're also attractive. I have been impressed over the years with the choice of posters that teachers make. Some of the sayings quoted are from well-known, historical personalities who have made an impact on society.  For example, I saw one by Benjamin Franklin that said, "An investment in knowledge always pays the best interest." I like that. It really resonates with me. And what about this quote from Coco Chanel, "Success is most often achieved by those who don't know that failure is inevitable."(1) I suspect that only the oldest students in the High School will appreciate such quotes, but I could be wrong(2). I know that the teachers certainly appreciate the encouragement that they see on the walls. It can be a good practice to surround ourselves at work with positive words, so we remember our goals and our potential. I think it is easy to forget those things when we are tired or under stress(3). I suppose they could also serve as teaching points that can be shared with the students, at one point or other. Einstein is a person who is quoted a lot in schools, and not just in the Science departments; his picture is recognized everywhere. Even little children in elementary school know that he was a genius of some sort, even if they don't know everything about his life. One of his many quotes that I enjoy is about acceptance and individuality, "Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid." This is a good one for a school environment. The children are emotionally immature, of course, so they might judge themselves or others far too harshly, instead of embracing differences and uniqueness. 

1. 'Inevitable' means that something is definitely going to happen. We also use it in an adverbial form a lot.

a. If the builders don't build the house according to code, there will  inevitably be a disaster.

b. He is the most qualified and experienced for the job; it's inevitable that he will get it.

2. 'I/you/he/she ... could be wrong' this is a wonderful extra sentence that we add onto a preexisting one. It states something obvious in order to show a little humility, and familiarity.

a. Your house will probably sell in the spring, but I could be wrong. 

b. We think he will give up his candidacy, but we could be wrong.

3. 'To be under stress' is the same as 'to be stressed'. I think it sounds more native because it is more of an idiomatic phrase.

a. I'm sorry I'm so tired; I'm just under a lot of stress recently.

b. They must be under a lot of stress because their business is not doing well.