I hang this sign in my classroom to give students a better understanding of main idea. I learned this in a CORE Connections training which is gearing more towards Common Core Standards. The topic is in blue because you would circle the topic in blue. The point is in red because you would underline the point in red. The supporting details is in green because you would underline the supporting details in green. You need to refer to this sign as an addition sentence, so students get it.