Mother Roni Dean-Burren got a message from her son Coby, in which he snapped a shot of his ninth-grade McGraw-Hill World Geography textbook. In a section titled "Patterns of Immigration," the most that is dedicated to explaining how the majority of African people first made their way to the Americas is a speech bubble reading:

“The Atlantic Slave Trade between the 1500s and 1800s brought millions of workers from Africa to the southern United States to work on agricultural plantations.”  

Following that Roni's son wrote, "We was real hard workers wasn't we," along with a very expressive emoji. 

Sources: McGraw Hill Education | Roni Dean-Burren