Classroom ideas for teaching oral health week for 1st graders?

Ask a local dentist. Dental offices often will go to local schools to educate the kids and give them toothbrushes. Ask a few offices in your area. I believe they will be happy to do it.
Video for the class. You can find videos on google if u search for cartoon for kids on oral hygiene. You can play that in the classroom.
ADA website. American dental association has ideas for educators in their smile smart oral health curriculum. have fun!