What is an expressed topic sentence?

Expressed Topic Sentence: Expressed or explicit topic sentences directly reveal the topic and the key subject under discussion within the main idea.

Examples:

* "Many people enjoy walking; however, few know it's a great mode of exercising."

* "Reading offers readers many advantages. One reason, reading enhances focus."

* "Many things help students remember better, such as studying regularly and asking questions while doing homework. One great memory tip students can do is studying in groups while having snacks."