Simplify the following text for a Grade 5 native English-speaking person.
Original: Glasgow has three professional football clubs : Rangers F.C. and Celtic F.C. together known as the Old Firm , and Partick Thistle F.C. .
Simplified: Glasgow has several football teams - the best-known are Rangers F.C. and Celtic F.C. . Partick Thistle , Clydebank , and Queens Park F.C. also play in the city .