How do you promote critical thinking and problem-solving skills in STEM and STEAM projects?

Have students come up with their own questions, about things they are curious about. This will add interest to the activity. Ask students why they would ever need to know this in the real world. Linking it to either prior knowledge, perhaps a parent's profession, or future learning, what they want to do when they "grow up" can be a very valuable tool.

I do agree open-ended question is very effective to foster critical thinking. As an educator, we have to be mindful with the open-ended questions we choose. If the question is too general, students may get lost with too many possibilities. In my experience, we should choose open-ended question that is specific enough so students have enough time to find out at least one possible answer and then time to discuss their answers with their peers.

In this case, you could have students start by identifying situations where they might find properties of light, in situations they could study over time. The same with sound. Yes, we all see sources of light but what sources can be studied because they are either static or ever-changing? What about sound? Instead of providing students with opportunities for exploration have them brainstorm opportunities on their own.

Another example, instead of teaching about Archimedes' principle formular, you could start with a real life situation: "what happen with the water level in the ice - water glass after the ice melt down completely?"

Talk to students about step-by-step observations and why breaking it down into these steps helps us learn more thoroughly about what we are studying. Ask students if they think studying something in pieces is more beneficial than taking a whole topic all at once. For different topics there will be different answers depending on the student's experiences and what they already know.

Completely agree with encourage collaboration would foster critical thinking. When the collaboration tasks are managed well by giving time for students to share their perspectives among their group, it will promote their critical thinking along with communication skills.

I totally agree and I think it is so important to show students that sharing information helps the entire group as a whole because sometimes only one person may see something that the others have missed. Similarly, maybe one group is focusing on something that seems irrelevant to another group. This opens up discussion.

Students are often taught that reflection is like grading something and the purpose is to see right and wrong. In STEM and STEAM projects there isn't always going to be a definitive right or wrong and it is important to see that even two totally different solutions could be absolutely correct.

I believe the biggest piece of learning is asking students to identify what they want to learn, what they think would be important to learn, and then methods of finding that learning. It instills a bit of independence and opens up interest that perhaps a teacher or adult may not see or see as important. Listen to students. Let students talk.