Whenever you have a list of more than two items in a sentence each item in that list needs to be separated by commas. The best way to correct the sentence above is, "I really hate three chores in particular: cleaning, doing laundry, and mowing the lawn." Note that "doing laundry" and "mowing the lawn" constitute single items in the list. Also note that parallel structure must be maintained within the list.

Whenever you have a list of three or more things in a sentence, each item of the list should be separated by a comma.  As such, there should be a comma between "coordination" and "athleticism" in the sentence above.  

There should be no comma directly after "were." Commas are used to separate items in a list but not to introduce the list. No punctuation is necessary here.

This question tests knowledge of commas in lists. In Standard American English, it is convention to not put commas in lists if there are only two items and to put them in if there are three or more items. Since there are only two cities in the first part of the sentence (Boston and New York), there is no need for a comma. A corrected sentence would be "On her summer road trip, Kayli visited Boston and New York for a week each, and she stayed in Baltimore for three days."

This sentence is testing knowledge of the use of commas in lists. The standard practice is to use commas after the first and second items in a third (or more) item list. Sometimes the comma is omitted after the second item, but this omission can be confusing because it can suggest a unintended connection between the second and third items, as it does in this sentence. Presumably the father is not packing sandwiches with peanut butter as well as pickles on them, and instead he is packing sandwiches with peanut butter as well as pickles seperately. Therefore, the sentence should read: "For the Fourth of July picnic on the White House lawn, Luke's father packed salads, sandwiches with peanut butter, and pickles for the children, but unfortunately, he forgot to pack water."

Since there is a list in the sentence, there needs to be a comma after "play." Without a comma, the reader would read "play walk" as one activity.  

This sentence has no error. Commas correctly separate all items in the list, and there are no other grammatical errors.

There needs to be a comma after "tents" since this sentence contains a list of activities the children completed. Items in a list of tree or more items must all be separated with commas.

Since "need" is a verb, it is not a part of the list of nouns. There does not need to be a comma after the word "need."

There should be a comma after "ice cream" since this is a list of activities Martha would like to do. A list of three or more items should have a comma followed by an "and" right before the last item in the list.