From the original high-school newspaper article (quoted here):
In an email to the Booster, Robertson also said she had a teacher certification from the University of Cambridge UK. The University of Cambridge confirmed that they offer that degree.
If it’s a teacher’s certification, it’s the PGCE (which Cambridge do offer). You’re correct that it’s not a degree, but I think an American high-school student might not know the difference. It partly depends on the phrasing of this email and how the journalists phrased their question to Cambridge.
There is also the PGCE-MEd programme at Cambridge- but again they are qualified to teach after the PGCE, it just means that they can do the MEd more quickly.
Incidentally, the paragraph I quoted continues:
. Also during the conference call interview, Robertson said she received a bachelor’s of fine arts (BFA) in theater arts from the University of Tulsa (UT) in 1991. The Booster continued to fact check Robertson’s education and contacted UT. According to the registrar’s office, a BFA has never been offered at the institution. The university was specific in the degrees offered; only a bachelor of arts in theater was available at that time, not a BFA.