Obama planned to view students' projects in the East Garden and State Dining Room in the afternoon as part of his "Educate to Innovate" campaign, a White House news release said.
Children participating in the science fair are the winners of a wide range of science, technology, engineering and math competitions from across the country.
The first White House Science Fair took place in 2010, and was aimed at motivating students to excel at math and science, the release said.
"If you win the [National Collegiate Athletic Association] championship, you come to the White House. Well, if you're a young person and you produce the best experiment or design, the best hardware or software, you ought to be recognized for that achievement, too," Obama said at that time.