idiom
teach an old dog new tricks
年齢や経験のために学ぶのが難しいことを誰かに教えようとする
Meaning
to try to teach someone something that is difficult for them to learn due to their age or experience
Example
It's hard to **teach an old dog new tricks**, but I'll try.
古い犬に新しい技を**教えるのは難しい**ですが、私は頑張ります。