1. Why are signs easier to acquire than speech?
2. According to researches, what are the corner stones of communication?
3. How does Jenna know that the green puppet is something she can communicate with?
4. At 18 months, how many words do babies know? Which types of vocabulary are high on the list?
5. What is “language explosion”? When does it come?
6. What conclusions can be made from the experiment “shape bias”?
7. How large is human vocabulary at the age of 2?
   

https://www.youtube.com/watch?v=4-cUBMRXAas&list=PLU4QkAf6LLaPcAPZ_yqyTlINqKar852mr