Simplify the following text for a Grade 5 native English-speaking person.
Original: For the season Bahrain was again the season opener and Formula One cars drove the full 6.299 k `` Endurance Circuit '' to celebrate F1 's ` diamond jubilee ' .
Simplified: In , Bahrain was the first race of the season . For 2010 , the Formula One cars raced on the full 6.299 k `` Endurance Circuit '' .