The article "Turning Traditional Textbook Problems into Open-Ended Problems"by Kabiri and Smith talks a lot about the same concepts. It is important for children to be responsible for their own learning and be put to a challenge rather than passively sitting there. However, this article brings attention to the idea of challenging all different types of learners. The article mentions that most teachers aim towards the needs of middle learners (versus lower or higher). By using open-ended questions instead of traditional questions, learners of all levels can work out the answer in their own way. I know that many textbooks create open-ended questions, but even if they don't teachers can find problems to manipulate to be more open-ended. Having students do open-ended questions makes them feel more comfortable at their level while also putting them in the driver's seat of their own learning. It gives students the opportunity to discuss and work out problems both with other students and on their own.
I have noticed that my MT has encouraged a lot of participation when she teaches math lessons. She likes the students to ask questions and work out problems while she teaches. She knows that she will lose the students attention if she lectures for long. Students do not learn well just sitting there listening. I have not noticed if my MT has tried to use many open-ended questions within her classroom, but I know it would be helpful with the amount of different levels throughout the classroom.