A teacher before beginning to teach 'digestion' to class VI students provides them with the outline diagram of a human body and asks them to draw all parts, through which they think the food would travel from mouth when they eat.What could be the teacher's purpose of asking this question?

To investigate students' prior ideas related to human body and digestion so that future teaching learning sessions can be accordingly planned

To find out which students have read the topic in advance and come prepared for the class and grade them accordingly

To evaluate students' drawing skills as drawing diagrams is an important skill in life sciences

To judge students' understanding of the digestive system and grade them accordingly