Final answer:
The punctuated sentence should read: 'At the art class, Sonja learned to paint a picture of a dog.' A comma is used after the introductory phrase and 'Sonja' is capitalized as a proper noun.
Step-by-step explanation:
To properly add punctuation to the sentence 'at the art class sonja learned to paint a picture of a dog', we must consider the intended meaning and the structure of the sentence in terms of introductory phrases, independent clauses, and lists.
From the information provided, the sentence begins with an introductory phrase describing the location where an activity took place. According to the learning objectives, we use commas after introductory phrases. Therefore, the correct punctuated sentence should be: 'At the art class, Sonja learned to paint a picture of a dog.'
This sentence has a clear subject which is Sonja and the verb 'learned' indicating what activity was performed—painting a picture of a dog. The introductory phrase 'At the art class' is followed by a comma. The name 'Sonja' is a proper noun and should be capitalized. There's no need for a semicolon or a colon in this sentence as there is no list or second independent clause being connected or introduced.