Simplify the following text for a Grade 3 native English-speaking person.
Original: The 5000 metres ( approximately 3.1 mi or 16,404 ft ) is a popular running distance also known as 5 km or 5K ( `` five-K '' ) in American English .
Simplified: The 5000 metres ( about 3.1 mi or 16,404 ft ) is a popular running distance . It is also known as a 5K or 5 km .