One problem that students always seem to encounter is related to whether the letter "-t" is silent in the end of a word or not. This is because the majority of language books don't deal with the issue.
The basic and simple rule is that nouns in the definitive form has a silent "-t".
Verbs (or adjectives for that matter) don't have a silent "-t". The verbs are the ones making the most confusion when starting to learn about past tense.
Most verbs don't look like a noun, but the verbs in group 1 have "-et" in past tense. Just what you will find in definitive form of neutral nouns. E.g. Et hus - Huset (silent -t); Et eple - eplet (silent -t). Whereas the -t in past tense of verbs is silent. å rydde - rydder - ryddet (not silent -t).