Traveling from US to Australia this summer. What the best way to deal with money?

My nephew will be traveling from Michigan to Australia with the People to People organization this summer. What is the best way to deal with money? I was wondering if there is a money/debit/credit card that could be used internationally, and his parents could monitor online and add funds to if the balance got low, or turn off if it gets stolen.

Our money in USA is worth more,now. try AAA club. You can buy travelers checks in foreign currency.

Most big banks are world wide. Check with his bank, and use the debit card as you mentioned.

Have a look at https://aussiedebitcard.com/
I've been using it while in Australia, very satisfied.

Easy, Debit Cards work down under, only problem if he loses the card or it gets stolen, you have to try to get him another one. Also, you have to teach him the exchange rate, so he understands how much of there money equals to 1 US Dollar.