SAN DIEGO -- Former astronaut Bernard Harris talked with middle school students and teachers in San Diego Friday about achieving their goals, in the first stop on his "Dream Tour."

Harris, a physician and the first black American to walk in space, spoke to about 650 students from Millennial Tech Middle School, Innovation Middle School and Memorial Preparatory School at Abraham Lincoln High School.

The tour, sponsored by the ExxonMobil Foundation and The Harris Foundation, is intended to reinforce for students the importance of acquiring strong math and science skills.

"It is critical that American students are prepared with the problem- solving skills and tools to tackle challenges they may face in the future," Harris said. "Providing them with a strong foundation in math and science education is imperative, and with The Dream Tour, I hope to inspire students to pursue studies and careers in these fields."

Harris will also make stops in Anchorage, Baton Rouge, Billings, Cleveland, Denver, Nashville, Philadelphia, Phoenix and San Francisco.