What were your own school days like?
I was allergic to school. I was completely befuddled by school. I was trying so hard but I couldn't succeed. I took geometry for four years, the same course over and over again and I did not graduate with my senior class. I finally passed geometry after doing summer school and eventually I graduated. But after all that at no point in my professional life, from June 30 1970 when I graduated to May 2014, not one human being has said the word hypotenuse to me! So did I really have to feel so bad and struggle so much and think I was so stupid for so long? I really feel we have teach children how they learn not what we think they should learn at school.

Are the teachers in your Hank Zipzer books Miss Adolf and Mr Rock based on real people?
Yes. Miss Adolf is based on my real teacher and she was a horrible teacher. Mr Rock (the character I play in the TV version of my Hank Zipzer books) is based on my real teacher and he was the man who said to me "Winkler (teachers called kids by their surnames in those days) when you get out of school you're going to be okay". Those words meant everything to me.

Why did you decide to write the Hank Zipzer books?
It was an accident. My agent suggested it to me and at first I was shocked, me write a book? I thought I couldn't do it, I thought I was too stupid to write a book. Even though I was a famous actor, I still thought I was stupid because I'd been told that so many times at school. It was imprinted on me and that's why I think it's so important that parents, teachers, librarians, carers don't even joke about a child being stupid. All children know when something is wrong and they can't understand something – they never need someone to tell them they're stupid. They need help in solving the problem. I wrote the books mainly to make the reader laugh first and they just happen to be based on someone I know very well, me.

Do you have a favourite of your books
I have now written 26 books, 18 in the Hank Zipzer series and four in the Ghost Buddy series. I don't have a favourite, they are like my children how can I have a favourite?

You write with a partner Lin Oliver, how does that work?
Lin sits at the computer and I talk, she types. Lin reads it back to me and we argue over it. If if doesn't make us laugh then it doesn't make the book. When I'm writing all the emotions of Hank come through me, I remember in so much detail what it's like to be a kid.

Did you have a favourite book when you were young?
No. I didn't read a book until I was 31 years old when I was diagnosed with dyslexia. Books terrified me. They made me nervous. Now I know you can travel to the bottom of the ocean or to outer space or anywhere in between without leaving your armchair and I'm so, so sorry I couldn't read when I was younger. Now I read thrillers and every one I've read is a triumph for me. They are lined up on my shelf like trophies. I also read books to my grandchildren who are aged four and two but reading is still difficult for me. I read very slowly.

What special steps do you take to make it possible for children who have dyslexia or have trouble reading to read your books?
We think about those kids all the time, although all types of readers read my books. One thing we do is have a lot of white space in the books. Sometimes a chapter is 12 pages long, but sometimes it's a paragraph long. Sometimes it's a list. If a child has a hard time reading, they can still read a whole chapter of my books. Kids who have never read before, reluctant readers, can read my books.

What advice would you give your 10-year-old self?
Henry: you are not defined by school. No matter how difficult it might be it has nothing to do with how brilliant you are. Your grades do not define how brilliant you are. Good thinking and a good thought is why you are smart.

You are very famous from playing The Fonz in Happy Days to adults of a certain age, does it bother you that kids don't know who the Fonz is?
No, not at all! In fact lots of kids know me as Mr Rock now from Hank Zipzer but their parents can be particularly ferocious about getting a picture of me, I guess that doesn't happen to other authors so much! The funny thing is kids don't always know me but they often write to me and say how do I know them so well? That makes me proud!