Last updated at 08:18

What would you change in the world?

To enjoy the CBBC Newsround website at its best you will need to have JavaScript turned on.

What would you change in the world by the time you're grown up?

Thirty primary school children from across Wales have written postcards about their hopes for the future, to world leaders who arrive in Newport for the NATO summit - a big meeting of some of the world's most powerful people.

The messages from nine and ten-year-olds will be given to Prime Minister David Cameron and US President Barrack Obama.