President Obama hosted the third White House Science Fair yesterday, taking the opportunity to recognize the accomplishments of students who have science fairs and to announce the launch of a new AmeriCorps track focused on STEM education.

After touring the exhibits brought to 1600 Pennsylvania by 100 students from 40 states, Obama said: "Let me just start by saying, in my official capacity as president: This stuff is really cool. And I want to thank these incredible young people for explaining to me what the heck is going on."

As we've noted before, Obama has talked repeatedly about the importance of STEM education, including in his State of the Union address this year. He hosted the first White House Science Fair in 2010. STEM advocates say he's used the bully pulpit to great effect in promoting the cause.

"We need to make this a priority to train an army of teachers in these subject areas, and to make sure that all of us as a country are lifting up these subjects for the respect that they deserve," he said. "And we've got to give the millions of Americans who work in science and technology not only the kind of respect they deserve but also new ways to engage young people."

To that end, the president announced the new AmeriCorps program for STEM education. The new effort will be a "multiyear initiative" to place hundreds of AmeriCorps members in nonprofits around the country to help "mobilize STEM professionals to inspire young people to excel in STEM education," according to a press release from the Corporation for National and Community Service, which oversees Americorps.

In its first phase, the press release says, 50 full-time AmeriCorps members will be placed with FIRST, a nonprofit founded by inventor Dean Kamen that aims to engage students in the STEM disciplines through robotics competitions.

At the White House event yesterday, Obama also announced that a group of technology companies and nonprofits have launched a campaign to encourage businesses to commit 20 percent of their STEM employees to 20 hours of mentoring or teaching by 2020, according to a White House blog post on the science fair.

A White House fact sheet provides background on these and other initiatives, as well as exhibits on display at the science fair.

On the policy front, meanwhile, Obama unveiled a number of new STEM education proposals in his latest budget request, including a $35 million STEM Master Teacher Corps and a STEM Virtual Learning Network.

You can read about the president's second White House Science Fair here.

President Obama pedals a bicycle-powered emergency water-sanitation station for Payton Karr, 16, left, and Kiona Elliott, 18, center, both from Oakland Park, Fla., to help demonstrate their invention in the White House's East Garden. --Pablo Martinez Monsivais/AP

