Plain past tense ( also known as た form)

Question 1

How do you change plain form weak/ichidan verbs into past tense?

Answer 1

Replace る with た

e.g 食べる　→　食べた

Question 2

How do you change plain form strong/godan verbs into past tense?

Answer 2

Depends on the final letter in the verb stem.
る or つ ending - replace final syllable with “った”
乗る noru → 乗った notta

く ending - replace final syllable with “いた”
書く kaku → 書いた kaita

す ending - replace final syllable with “した”
話す hanasu → 話した hanashita

ぶ , む or ぬ ending - replace final syllable with “んだ” 遊ぶ asobu → 遊んだ asonda

“gu” ending - replace final syllable with “いだ”
泳ぐ oyogu → 泳いだ oyoida