My child..

Ok so my child is mixed. He is Costa Rican, Cuban, Puerto Rican and African American.( I am more than one race but define myself as AA) My son is 7. Well, yesterday I was showing him a picture of my brother skydiving with an aid. He pointed out that there was a slave with a 'nonslave' in his words. I asked what he meant. He said uncle Joseph is a slave and the white person isn't. I asked why he thought that. He said uncle Joseph is brown and the other person is white. I ask where he learned that. And he said all of the books in school say that brown people are slaves. So I corrected him saying brown people used to be but aren't anymore. I asked him what he thought his daddy was and his dad's side of the family. He said they're white. I told him they weren't white. They are Hispanic. He wouldn't agree with me on that. Seeing as his dad is tall and light being he is half Costa Rican. Plus I don't want him going around school saying or thinking brown people are slaves. He goes to a predominantly white school. But our family is a huge melting pot. My stepmom is white. My husband is Scottish and Irish. My Older SIL is white. My younger SIL is Mexican. And my family is AA. So I am just trying to wrap my head around his way of thinking. Any advice? I want to ask my mom. But even though my different races come from her side. (Her mom is AA and Indian. Her dad is white) she is a very proud black woman and I know she will give my poor son a two hour lesson and make him read all kinds of books and stuff. Smh. So any advice on tackling this would be great. Thank you! Below is my son and his father. I can see why he thinks his dad is white.