t-shirt mask back over the mouth. From your beloved CDC itself... respirators (n-95s) should be fit-tested at a minimum annually, with each brand/model of respirator used and also with changes in weight, etc... to insure the respirator provides the expected benefit. For those of us who actually work in healthcare, we know kids wearing masks are useless. kind of like expecting they are washing their hands after playing with toys that other kids have handled and they don't touch their face until they do.
Link: https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3fittest.html