She spoke with them about feeling racially isolated in school when they leave their community.

Michelle Obama made a stop on the Gila River Indian Community ahead of her book tour event in Phoenix Tuesday night.

The former first lady surprised students at the Huhugam Heritage Center for a roundtable meeting with GRIC Governor Stephen Roe Lewis.

The young people Obama met with were high school and college students from the community.

They were in the middle of a discussion when Obama and Valerie Jarrett, a former top aide to President Barack Obama, walked in. The students were stunned to be greeted by someone they'd only seen on television before.

Obama asked the students to share a little bit about themselves, and the group discussed feeling racially isolated when they go to school or work away from the community.

The surprise came hours before Obama makes the next stop on her Becoming book tour Tuesday night at Comerica Theatre. Her memoir has topped the NY Times' bestsellers nonfiction list for the last 12 weeks.