Evaluate the similarity between them and classify them into classes from 0-5 as follows:
0 : The two sentences are completely dissimilar.
1 : The two sentences are not equivalent, but are on the same topic.
2 : The two sentences are not equivalent, but share some details.
3 : The two sentences are roughly equivalent, but some important information differs/missing.
4 : The two sentences are mostly equivalent, but some unimportant details differ.
5 : The two sentences are completely equivalent, as they mean the same thing.

Sentence 1: They know that the video doesn't show a gas chamber. Sentence 2: The bottom line is that the video clip doesn't show a gas chamber.
5

Sentence 1: Someone is playing piano. Sentence 2: A person is playing a keyboard piano.
4

Sentence 1: A skier speeds through the snow. Sentence 2: A brown dog carrying a Frisbee runs through the snow.

0