Simplify the following text for a Grade 7 native English-speaking person.
Original: The NHL 's Phoenix Coyotes and NLL 's Arizona Sting began playing in Glendale when Jobing.com Arena ( formerly the Glendale Arena ) opened in December 2003 .
Simplified: The NHL 's Phoenix Coyotes and NLL 's Arizona Sting started to play in Glendale when Jobing.com Arena opened in December 2003 .