This is a complete lesson plan to teach how to speak large numbers (up to and including the trillions). Included is a detailed lesson plan with teaching tips and activity cards to print on 4 x 6 index cards. The activity cards have large numbers on one side and their word equivalents on the reverse. Students collect "autographs" from each other as they correctly speak the numbers on the activity cards.
I've used this activity in adult ESL classes, but it would be equally effective in a non-ESL classroom. I like that the students (not the teacher) are correcting each other and also that the students are up and moving around the classroom.