Assert

Assert refers to an utterance where a fact or an opinion is stated confidently. In other words, assert refers to the statements where "The speaker is trying to make the addressee adopt a belief by communicating a claim about the world".

Example (1):
 -Explainer:['So have you ever heard of something called a black hole?']
 -Explainee:['What is a black hole?']
 -Explainer:[Well, it has to do with, a lot with gravity, 'do you know what gravity is?']---> Assert
 -Explainee:['No, not at all.']
 -Explainer:[It's what keeps us on the earth.]---> Assert