Help with wording of a question

Hey everyone.. so this isn't really a math problem, but it kind of is at the same time. I have something that I need to hand in on Monday, but the system in which I can contact a teacher from my coorespondence course will probably only get me a reply by Wensday. I was wondering if you could help me to determine what they want in this question:

h=-5t^2+30t+10

d) Determine the instantaneous velocity of the flare at t = 3 seconds by using the slopes of secants. (3 marks: 1 for table, 2 marks for slopes)

Now, I am wondering, for the slopes of secants, are they implying that I should graph them or just figure them out in my table?