Maybe we can find an exception for George Washington, but I cannot think of any time that I have ever heard school children singing praises to an American President in a Public School, or at any other time for that matter.
When I expressed my concern about my child participating in the President's speech to the children, this type of activity is exactly what I was afraid of.
I don't now where the school is that the video was taken, nor do I know what class this was being taught in. However I can think of no context in which it is okay to teach any child to worship a politician.
What's worse, they are using the melody of the Battle Hymn of the Republic.