The past tense is used for things that have already happened. He was sticky. The present tense is used when something is happening now or when something happens regularly. He is sticky.

The usual practice is to have the present tense express a current event while the past tense indicates the past. But there is a dramatic situation the present tense can state a past occurrence too.

One’s tense will vary depending on what one is trying to convey within their paper or section of their paper. For example, the tense may change between the methods section and the discussion section.