Most students by the time they leave middle school have received an intense grounding in grammar rules; however, by the time they get to college, many of these same students discover that their freshman composition teacher has counted off for a rule they have supposedly known for many years. What gives? The students have simply forgotten the last part of the rules.
First let's tackle the colon:
Rule 1: Use a colon to introduce a list.
The part of the rule that students forget: But don't separate the subject from the verb with the colon.
Wrong: We need: bread, cheese, and wine.
Reason: It's grammatically incorrect to separate the object of a preposition or an indirect object or direct object from the verb with a colon.
Wrong: We need to buy: bread, cheese, and wine.
Right: We need to buy bread, cheese, and wine.
or
Right: We need to buy these groceries: bread, cheese, and wine. (The writer can also use a dash in this instance: We need to buy these groceries--bread, cheese, and wine.
Rule 2: Use a colon to break up a long sentence.
The part of the rule that students forget: But only do so if the part of the sentence following the colon acts as an apositive (a noun that renames the subject before it).
Example: Now let's get back to those groceries: bread, cheese, wine, tomatoes, butter, eggs, and flour.
Rule 3: Use a colon in a business letter or memo (this is an easy one).
Examples:
Dear Sir or Madam:
To whom it may concern:
Now for the semicolon:
Rule 1: Use a semicolon to separate items in a series.
The part of the rule that students forget: But only do so when not having a semicolon would make the sentence confusing.
Example of a confusing sentence: Our student council elected Emily, President, Chantrelle, Vice President, Jim, Treasurer, Sam, Parliamentarian, Jackie, Special Events Chair, Shondra.
Example of the same sentence with semicolons: One student council elected Emily, President; Chantrelle, Vice President; Jim, Treasurer; Sam, Parliamentarian; Jackie, Special Events Chair, Shondra.
Rule 2: Use a semicolon to separate a really long sentence into two separate sentences.
The part of the rule that students forget: But make sure that the two parts of the compound sentence are connected in content.
Example: We need to buy some school supplies; the sale ends next week at the office supply store.
Usually, a semicolon followed by a transition word and a comma works best in sentences like these. Choose from words like however, nevertheless, incidentally, moreover, similarly, and incidentally.
We need to buy some school supplies; incidentally, the sale ends next week at the office supply store.
Incidentally, I've taught college freshman composition and rhetoric for more than ten years, but I'm now teaching at the secondary level.
