*TRIGGER WARNING* self harm & new job

So, before I begin, I am 6 years clean from self harm. I also have an almost 3 year old son. I recently got a job as a preschool teacher, and Im so excited! Mainly because my son gets free preschool and I can go back to college because I will have childcare. I start this coming week. However, I have self harm scars all over my arms. I really dont want the people who run the preschool to see my arms like this, nor do I want the little kiddos or their parents to see them and question it. Im not really sure how to hide this. Ive thought about makeup, but Im not sure what kind of foundation/concealer would give me the coverage Im looking for. Ive also thought about long sleeves, which will be fine in the winter, but its so hot out here I know Ill be sweating all day and people would wonder why I am wearing long sleeves in the summer lol. Im kinda at a stand still right now. I want to be honest with them but Im worried that would sacrifice my job, because they care very much about the appearance of their teachers, which I completely understand. Any ideas are appreciated!