Recently, one of my students got tripped up on this question (#34) from an SAT practice test:
He knew that A, B, and D were wrong, because each changes the verb tense for no reason. But he didn't like C, either; he thought there might be a subject-verb agreement error.
My student saw:
"There ARE a number of steps..."
and thought it should be:
"There IS a number of steps..."
After all, "a number" is clearly singular. Shouldn't it take a singular verb?
Not in this case! My student had unwittingly stumbled onto an example of that two-headed beast - the collective noun.
Collective nouns (group, faculty, team, staff) can function either as singulars OR plurals, depending on what's being emphasized:
The team has survived the playoffs, but the World Series will be the real test.
Here, "the team" functions as a single unit, so we use a singular verb.
The team members have agreed to treatment after a drug-fueled Las Vegas blowout.
Here, "the team members" are acting individually, so we use a plural verb.
In my student's example above, "steps" are clearly individual elements of a career journey, so we consider them separately and use the plural "are."
American vs. British English
If you read authors from both sides of the Atlantic, you may have noticed that Americans and Brits treat collective nouns somewhat differently. American writers are more likely to use singular verbs for collective nouns; British writers favor plural verbs more often.
American: The staff has agreed to a pay cut.
British: The staff have agreed to a pay cut.