This question seems to answer itself if you look up what the words mean. "Main idea" means the most important idea, and "supporting" means ideas and details that back up the main idea and give supporting evidence for it.
to give the details or arguments that support the main idea
Supporting sentences use ideas and facts to support the thesis or main idea.
What is the main idea of the text? (What is the text about?) How does the author support this main idea? (What evidence or key points are used to convey the main idea?)
a statistic
supporting details
setting
458
The supportibd details support the main idea
Find the main idea of the paragraph and the look for the details that support the main idea. A good way to do this is to underline the main idea and then circle the details as you read the paragraph.
Facts
The climate
Facts