Thirty teams from New Hampshire are participating in the regional competition for FIRST Robotics at the Verizon Wireless Arena in Manchester this weekend. They include high school teams from Amherst, Bedford, Hollis, Litchfield, Merrimack, Nashua and Windham, and a home-school group based in Milford.

It’s the 20th year for the competition developed by Manchester inventor Dean Kamen, which has grown from a few teams in a high school gym to a worldwide event that draws in more than 50,000 high school students.

Contests, in which teams of robots try to stack tubes in specific patterns, run all day today and half of Sunday.

Hundreds of fans, including cheerleaders and people in weird costumes, show up to cheer.

The event is free to watch. You can wander in at any time and watch as much as you’d like.