[I love my furkids!]

I have two upcoming interviews. One is for a teacher with kids that are infant, toddler, and preschool age. I can do that job right now. The other is to get my alternative teaching certification and teach kids anywhere from K-12. The pay is a little less for the younger kids but not by much. I am not a very aggressive person, I consider myself a nice person and I try to avoid confrontations. I worry if I teach the older kids I wouldn't be able to handle the "mean" kids. What do you think?
If i do the younger kids I can start working right away, if I do the older ones I'll have to get my certification first so won't start working until August. I am out of a job right now.