Talking about the open-ended problem: Find a mean of ten (you can determine how many numbers they use to find a mean of ten).
Instructional strategy that can be used with open-ended questioning.
Further explanation of this instructional strategy.
How do NCTM's math teaching practices connect with open-ended questioning.
Open-ended questions open up the possible answers and opens it to more students participating based on their level of understanding.
Understanding mathematics at a deeper level is more important, than giving 20 practice problems.
Sometimes, the simplest open-ended question can promote the richest student discourse.