Which punctuation change will correct this sentence The note from the band director read Tim has great potential however lack of practice slows his progress toward mastery.?

The correct punctuation change is to add a semicolon after "potential."

Here's the corrected sentence:

The note from the band director read Tim has great potential; however, lack of practice slows his progress toward mastery.

Here's why:

* Semicolons are used to join two independent clauses (complete sentences) that are closely related in meaning.

* "However" is a conjunctive adverb that introduces a contrasting idea. It requires a semicolon before it when it joins two independent clauses.

Without the semicolon, the sentence is grammatically incorrect because it creates a run-on sentence.