I sent home this parent volunteer questionnaire at open house this year. I included a section where parents could sign up to volunteer in the classroom on a weekly basis for timeslots that I decided on before hand. I've attached a word document file with my information still on it for you to have as an example and can edit yourself. I've also included a blank PDF form that you could just print out and write in your information in the time slots.
I used the fonts DJ Doodlers and ABC Print so you may need to change the font if you decide to edit it.