A teacher encourages the children in her class to explain the physical properties of the objects around them in their own words.

What is the most appropriate objective of the teacher to do such an activity with her students?

As a teacher, you are responsible for creating an environment where learners fully involve in process of mathematical thinking or knowledge generation; so that it can energize the construction of new mathematical concepts. 

For example, a teacher was developing her/his teaching of the concept of physical properties of the objects for teaching the class.

• If a child is told to express his observations about the objects around then he will be able to understand and observe the physical properties of objects around them carefully before reaching any conclusion.
• It will develop critical thinking and reasoning skills among the learner.
• It is the best way to make a child learn the concepts of shapes and other physical properties of objects around.

Hence, we can conclude that It makes the children observe the physical properties of an object informally which deepens their understanding of shapes.