Answer:
scaffolding
Explanation:
Scaffolding is a method of instruction in which teachers shows the process of solving a problem to the students and explain the steps as the students proceeds forward. After making a few explanations, the instructor then leaves students to work independently but help him only when he feels that is student is stuck and will need guidance. .
Here Dean was stuck while solving the puzzle and mary came to her rescue. This is clear example of Scaffolding