Final answer:
The correct word to complete the sentence is 'and', indicating the conjunction fitting for a list of activities. It aligns with proper punctuation practices and the importance of basic writing and reading comprehension skills.
Step-by-step explanation:
The appropriate word to complete the sentence 'John usually spent his summer studying basic math, writing, ____________. ____________...reading comprehension?' is 'and'.
This conjunction fits best because the sentence lists a series of activities that John spent his summer doing. The word 'and' is used to connect the final item in a list of three or more items. This usage corresponds with the guidance provided on practicing correct punctuation and understanding essential components in sentence structures, as well as reinforcing basic writing and reading comprehension skills at a 3rd- to 6th-grade level.
Moreover, the ability to employ correct grammar and punctuation, such as using conjunctions appropriately, is also a skill valued after high school graduation and higher education, reflecting what recruiters, like those in Nick Marelli's story, look for in potential hires.