President Barack Obama gave away the punchline at Monday’s White House science fair — he has taped a show for Discovery Channel’s Mythbusters and he didn’t get to blow anything up.

USA/“I was a little frustrated with that,” Obama said, before he introduced a team of high school freshmen who built a solar-power car, seventh graders who designed a better sports helmet and high school students who designed a new kind of motorized chair for a disabled classmate.

The White House Science Fair, designed to highlight improved science and technology education, was a kickoff to a week-long science fair on the National Mall that is meant to get Americans kids fired up about science, math and engineering.

The big news hook? Obama will appear on the television show Mythbusters. They will do a reprise of an episode that debunked the 2,000-year-old story about Archimedes, the Greek mathematician and engineer who supposedly rigged up a way to set fire to an invading Roman fleet using a system of mirrors to reflect and focus the sun’s rays.

In contrast, the kids whose projects were honored did succeed, including Diego Vazquez and Antonio Hernandez from Cesar Chavez High School in Phoenix, Arizona, who designed the motorized chair; Mikayla Nelson, freshman at Central Catholic High School in Billings, Montana, who with classmates built a carbon-fiber solar vehicle from scratch; and Jonathan Berman, Benjamin Kotzubei and Austin Veseliza from Los Angeles’ Mirman School, whose experiments showed that gel rubber in helmets is far more shock absorbent than foam.