"Táim ag múineadh mo pháiste."
Translation:I am teaching my child.
It depends on the dialect, and the function of the word. For example, in Connacht, it's /ə/ if used as a verbal noun, but it'd generally be /u:/ if used as the past autonomous (for first conjugation verbs), and /əx/ in the conditional.
In Donegal, it generally tends to /u:/ in all cases, I believe. I'm not sure about Munster.
I typed the sentence (listening exercise) starting with “Tá mé…”, and it is not accepted, but there is no way to report that (no “My answer should be accepted” option) :)
If she said "táim" and you wrote "tá mé", then your answer shouldn't be accepted for a "Type what you hear" exercise. (And I say that even though I can't tell whether she's saying "táim" or "tá mé" and it doesn't make any difference, grammatically).