I’m updating my resume to add a current job. I’m a graduate student that’s researching and creating lecture slides for a civil engineering class this spring. Both teaching and research assistant have specific meanings that don’t fit. Does it really matter or will potential employers just read the job description?
How does TA not fit?
Either way, yes it matters and no you won’t find a good way to tart it up.
TA generally refers to somebody that grades homework and exams, holds office hours, and might lecture on occasion. I’m just figure out what to put on a couple dozen slides.
Right now I’m going with “lecture preparation assistant.” I don’t think that counts as tarting it up.
If this is a standard grad student TA assignment – you’re paid a stipend in exchange for doing work to support a particular class – then I would just put teaching assistant. TA work covers whatever random work your instructor has you do, including writing class material, proctoring tests, and doing last minute runs to the Xerox room. If it’s an hourly job then I’d use whatever title you were given when you were hired.
Teaching assistant isn’t really an exclusive term that they’ll accuse you of fraud for co-opting. 
(I mean, not in the same way that calling yourself an engineer without a degree and license is.) As a TA I’ve given lectures, prepped course materials, and ate sushi while reading a novel - uh, I mean proctored an exam.