Shakespeare was a writer whose technique was advanced to such a point that he could transcend the rules (or conventions, if you prefer) that usually govern what can be done in written English. Therefore, his work is the best possible place to learn about syntax, grammar, sentence construction, poetic metre, rhetoric, and figurative language. A multitude of examples of each of the above are available for study and discussion, and the best thing is that all of it was done to create a combination of dramatic art, poetry and philosophy that still hasn't been surpassed. In other words, Shakespeare contains style and substance, both of which are necessary to engage young minds.