In case you're interested, the full speech is available at the White House website. I read it... it says do good at school. Nothing really controversial. I don't know how much Kristopher will even understand or if he'll know that's the president before they tell him :) My only concern was if the classroom/teacher activities were going to be more politically based since those aren't regulated by what has to be said. But Kristopher will be attending on Tuesday and will hear the speech with the rest of the class and I'm sure all will be fine.
The lesson plans for the teachers to use are also available at the White House link above.