There is a good, short video on Time for Kids that you could show your students for some background knowledge.
I really like this idea:
How cute is that? It would be great if you had a copy of the book We The Kids by David Catrow. It would be fun to start this as a collaborative document, using a tool like Padlet. Have each student contribute their idea of what it means to be a good citizen. Then transfer their ideas to paper and have each student sign the "Class Constitution". So cute!
I also found this website with some good resources. I doubt it will work from their iPads, but it could be fun to share bits of it whole group. Lots of information. If students can work independently from MacBooks or ChromeBooks, they could read the information and take the accompanying quizzes.
It would also be cute to have them do some kind of art project (maybe make a flag like this one):
This is simply made from cutting pieces of construction paper and gluing to a white piece of construction paper, then adding white fingerprint "stars". You could then have students take a picture of the flag with an iPad (or a picture of each of them holding their flags), and upload into an app like Skitch , Pic Collage or Educreations - anywhere they could add text to their picture and label it or write what they think a good citizen is.
If you're working from a Chromebook or MacBook (this next idea needs Flash so it won't work on iPads), it would be fun to use the Read, Write, Think Theme Poem creator and have them use the flag outline to create a poem about citizenship or patriotism.
I hope these ideas are helpful, or inspire some other awesome Constitution Day or patriotic lessons. If you try anything in your class, please share with me so we can post examples and ideas on this blog for others to see!
Happy Teaching and Tech-ing!