Simplify the following text for a Grade 8 native English-speaking person.
Original: South Australia chose to continue with the Union Flag as National flag until 1956 , when schools were given the option of using either the Union or Australian flags .
Simplified: In 1954 , the Australian Flag became the official Australian National Flag . The Australian flag is the most important flag flown in Australia , and must be given more importance than flags from other countries .