Asking students open ended questions 

When you are asking students questions and they provide a solution, try some of these to promote further thinking:

• Could you elaborate further on that point?
• Will you express that point in another way?
• Can you give me an illustration?
• Would you give me an example?
• Will you provide more details?
• Could you be more specific?
• Do we need to consider another point of view?
• Is there another way to look at this question?

https://teachbetter.com/blog/strategies-to-increase-critical-thinking-skills-in-students/