Answer:
The teacher is using a token economy.
Step-by-step explanation:
A token economy is a type of behavioral strategy that involves the use of certain reinforcements with the aim of modifying an individual's behavior - either to remove undesired behaviors or incite appropiate ones.
By complying with the therapist's instructions, the individual will receive tokens that can be traded for rewards.
In this case, the teacher wants Cristal to turn in complete assignments. This is achieved by offering Cristal a reward inside the basket in exchange of the proposed task.