A childhood belief about reading

As a little kid in pre-war New Guinea, my parents would read out the eagerly awaited letters from family in Australia - "Grandma asks if you are being a good boy, and Sport (her dog) still likes to play", - and so on. So I knew early that those marks on the paper meant real words, but I wanted to talk to Grandma too, and would scribble on bits of paper while carefully shouting out my message (I knew she was a long way away). But I thought it had to be like a conversation, so I would have to invent Grandma's reply and shout and scribble that too. But if I had to know what her answer would be before "writing" it down, what was the point in asking the question? I was a logical if rather confused child. Things haven't changed much.