I wondered the other day about these two words.

Problem:
One of these nouns formerly was a synonym for the other noun but now is not.

Explanation:
The noun “phonics”, which dates back to around the year 1680, refers to a way to teach spelling and reading based on the phonetic interpretation of ordinary spelling.

Put briefly, the primary meaning of the noun “phonetics”, which dates back to around the year 1840, is the study of speech sounds.

An obsolete meaning of the noun “phonics” is the noun “phonetics”.

Given that “phonics” is an older noun than “phonetics”, it seems that it was temporarily fashionable to use “phonics” as a synonym for “phonetics”, a much newer noun.

Note that one does not “teach phonics” unless one is teaching others how to use phonics for teaching spelling and reading.

For example, children in elementary school would not be “taught phonics”.

Instead, their teacher would “use phonics” to teach those children to read and spell, and that teacher would have been “taught phonics” by his or her college professor.

Solution:
Think “a way to teach” when thinking of the noun “phonics”; think “sounds” when thinking of the noun “phonetics”.