What observation indicates that students are engaged in mathematics discussions and modeling?

The observation that indicates students are engaged in mathematics discussions and modeling is when students are working in separate groups on different parts of the same topic. This scenario suggests that students are actively participating in collaborative learning. Engaging with peers allows them to discuss mathematical concepts, share different approaches to problem-solving, and understand various perspectives. It can also lead to deeper learning as they model mathematical ideas through discussion and group work, fostering an environment where mathematical reasoning and discourse are encouraged.

While the involvement of teachers can enhance discussions, the key indicator of student engagement is the active participation and collaboration among students, which is highlighted in the scenario where they are working in groups.