Final answer:
The best time for teachers to guide students' thinking, as they construct a mental model, is during reading.
Step-by-step explanation:
The best time for teachers to guide students' thinking, as they construct a mental model, is during reading. During reading, teachers can help students understand and analyze the text, make connections to prior knowledge, and develop a deeper understanding of the subject matter. By guiding students' thinking during reading, teachers can ensure that students are actively engaged in the learning process and are able to construct a mental model that is accurate and reflects their understanding.