My teacher was using your company's Power point presentations in class, and I just wanted to let you know that the keystone is portrayed incorrect, or better it is structurally unsound. In the pictures of the communication archway the trust "Keystone" block is portrayed as a triangle pointing up, when the triangle should be pointing down. You should probably fix that...Unless the point you wanted to make is that we cant relly on trust to keep our communication in tact....In which case good job, and also, I'm sorry for the people who know you, and the world you all live in.
Trusting in you,
PS. I figure you will want to know this so you can make a new version and charge people $100 for your mistake (you're welcome) but can I please have a free copy of the text book? I mean, I am providing you with a good excuse to make a new edition, and thereby not allow the schools to resell old books keeping money for themselves. You still come out ahead.