Final answer:
Ward's praise after Beaver learns new vocabulary words serves as positive reinforcement, adding a desirable stimulus to increase the behavior of learning.
Step-by-step explanation:
When Beaver's father Ward says, "That's a good boy, Beaver," after Beaver learns the meaning of ten new vocabulary words, this is an example of positive reinforcement. In operant conditioning, positive reinforcement is when a desirable stimulus is added to increase a behavior.
In this case, Ward's praise is the desirable stimulus that is added to encourage Beaver's learning of new vocabulary words. This type of reinforcement is often used effectively in educational settings to promote and encourage learning behaviors.