For the professional development day choose a plaid shirt to pair with black pants and a black blazer. (krembdelakremb.com)
I invested in a couple pairs of black pants along with a couple knit tops that I could pair with a business jacket if necessary. (natural-parenting-advice.com)
I have a pink blazer with navy trim and am always debating whether I can wear black pants with it! (thestyleletters.com)