What's the capital of Spain?

He'll thank me one day, but it wasn't easy for my son to learn two languages at the same time. I spoke to him in English, and his father spoke to him in German — not always at the same time. When he was speaking English, he would often mix up "I" and "me". Our corrections would only lead to confusion.

I'd always have to tell him that I was going to the toilet, so that he would know where I was. This was usually met with "I first!" as he would drop whatever it was he was doing and make a mad dash to take his place on the toilet.

My correction — "Me first!" — would only make things more competitive. "No. I!" he insisted. As if I would try to jump the queue ahead of a two-year-old with a weak bladder!

He's just turned eight, and although we don't fight over whose turn it is to "go", he still mixes up "me" and "I", especially in short statements that would require the German "ich".

He often says "I, too" instead of "me, too". This is known as language transfer — the effect one language has on another. (It used to be called "language interference", but that was thought to sound too negative.) Transfer can affect pronunciation, vocabulary, grammar and discourse (any connected piece of speaking or writing).

My favourite example of language transfer, though, comes from my daughter when she was about three years old. We were playing a game with my son. I asked him, "What's the capital of Spain?" Without hesitation, my daughter replied for him: "Spinat!"