Final answer:
The phrase 'to T-square' in the context should not be capitalized. The correct sentence should read 'to t-square'.
Step-by-step explanation:
No, the sentence "Martha's grandmother had to T-square before calculators were invented." is not capitalized properly. The tool 'T-square' should not be capitalized unless it's at the beginning of a sentence or part of a title. The corrected sentence should be: "Martha's grandmother had to t-square before calculators were invented." Capitalization is important in English as it helps indicate proper nouns, the start of sentences, and can alter the meaning of certain words.