Final answer:
The Golden Age of the Deaf or Deaf Renaissance is the period when ASL flourished and many teachers of the Deaf were themselves Deaf, highlighting the advancement of Deaf culture and education.
Step-by-step explanation:
The period of time when American Sign Language (ASL) flourishes and approximately 40% of all teachers of the Deaf are Deaf themselves is known as the Golden Age of the Deaf or Deaf Renaissance. This era, particularly strong in the late 19th and early 20th centuries, was a time of significant advancement in Deaf education and the promotion of Deaf culture. During this time, the use of sign language was highly encouraged, helping to preserve and enrich the Deaf community and its traditions.