Since this year was a special Pi Day 3-14-15 and they're retiring in 2015, it might be unique. I think pnw had the design for free, but I can't find it in my files now. If you google Pi Day Embroidery Designs you will find lots of sites that have it, either free or for sale. Have fun with it.
My daughter and I are both math teachers, and we are always being called nerds, usually in a nice way. We always say to embrace that inner nerd, that there's a little nerd in all of us. Urban Threads has some really cute "nerd" designs, if that would help.
Sue Dewsbury posted some chemical and molecules freebies here a while back. Perhaps you have them saved somewhere? I don't think we can access the freebies any more on this site.
I've seen the words "global warming ate my homework" with a snowman once, but I can't remember where. Maybe someone else knows.
Thanks I have Sues scientific designs but I am specifically needing math(s) In the UK where I am we call it Maths while I know that the USA says Math. I have asked in advance to give me time if something decent doesn't turn up. Then I will have a go my self