Conversations with my 15-month-old

Nathan is standing by a coffee table in a Martha’s Vineyard rental house playing with a stack of red and black coasters. Dad thinks this is a good time to work on his son’s language skills, and picks up a coaster of each color.
“Nathan, this is a red coaster. Can you say red?”
“Raaah.”
“Very good! And this is a black coaster. Can you say black?”
[blank stare]
“Okay, so maybe we won’t say black.”
“Baby!”
“Want to try again? This is the red one. Can you say red?”
“Raaah.”
“Right! And this is the black one. Can you say black?”
“Elmo!”