A 2nd grade teacher asks, "Boys and girls, look at the numbers 2, 4, 6, 8, ___. What comes next? What's the pattern?" In this case, the question is leading toward a specific answer (10).
An Algebra 1 teacher presents students with a set of data and asks them to plot two related variables on a graph. "What do you notice? What's the pattern?" In this case, the teacher is guiding the students to see a linear relationship in all the data.
A science teacher shows a data table of incidents of AIDS cases over a 15-year period, disaggregated by age, gender, region, and socioeconomic status. His question to students is "What's the pattern (or patterns)?" Instead of a pat answer, he intends to evoke careful analysis, reasoning, and spirited discussion.