I used to teach 4-H kids sewing....just always keep it fun for them...it is not life or death if they sew crooked! Remember this is a "love" that you are trying to inspire, not perfection! Kids learn at different rates and with different cues, be patient and kind, and it will all come together!
I agree with skipping the machine maintenance...that will come as they progress. I think that especially in this day and age..kids need instant gratification to keep their interest, so just keep it fun for them...the maintenance will come later! Good Luck...and thank you for inspiring another generation!