Planning effective questions to engage students in building their thinking skills is very important. You have to know how to plan your questions, otherwise your students will be less motivated to think. The questions should not be way too hard or too easy.
The Bloom's Revised Taxonomy of Thinking can really help you with this. Using question staircase which is basically based on the taxonomy, you can differentiate, grade, and sequence the questions from easier to more challenging ones.
Happy reading and happy teaching.