How to teach subtraction to a child who loves trains? A method tried using 'coupling and uncoupling'

Hey there.My son loves trains.Trying to teach him subtraction, I once drew a picture of the Komachi and Hayabusa trains ...

[For Parents of 1st Graders] How to teach subtraction with regrouping. 4 things you can do at home for children who get stuck on "13-8"

They have a look on their face that says they don't know what to do because you can't subtract 8 from 3 in the ones place.In ...