I'm in 5th grade, preparing a flyer for a fundraising fair. In the flyer, I need to call out an activity, coloring activity, which would be offered for free to all who purchased the coloring books. I would really appreciate your help getting this phrase grammar-proofing.
"Don’t have colors? – no problem! – participate in a free coloring during the event"
OR
"Don’t have colors? – no problem! – participate in free coloring during the event"
Should there be "a" before "free coloring" or not? I thought it should be because it's an activity = coloring. I couldn't get my teachers to agree on one vs. other. Please help!