Complex sentence: The Australian National Schools Debating Championships (abbreviated as NSDC) is a debating tournament held by the Australian Debating Federation (ADF), and contested annually by eight teams of high school students from each of Australia's states and territories.
Split into simpler sentences: The Australian National Schools Debating Championships (abbreviated as NSDC) is a debating tournament held annually by the Australian Debating Federation (ADF). The championships are contest by 8 teams of high school students from each of Australia's 8 states and territories.