The best way to combine these ideas is the third sentence. The first sentence is an "if, then" statement, which does indicate how things actually were when Shakespeare was in school. The second sentence implies that the school day was long during Shakespeare's time because the teachers were strict, which is not effective, because the two facts are not related. The final sentence is not properly formatted, so it is confusing for the reader. The third sentence, however, simply states two facts about schooling during Shakespeare's lifetime that provide concrete information.