We travel to Prague in about five weeks with 31 high school students. I am getting mixed messages about whether to use Czech currency or Euros. We are in Prague for 4 days and spend an afternoon at the Punkva caves near Brno. All our other destinations use the Euro. I welcome advice from recent travellers.

When I was there in October the currency was Czech koruna, not euro.

Many street vendors were happy to accept euro, albeit at an exchange rate favorable to them.

Unless things have magically changed in 3mo, you will definitely need Czech koruna (crowns). There are ATM's around Prague, so you won't need koruna before you arrive - just use the ATM at the airport so you have some in your pocket for spending cash.

What a wonderful opportunity to give them a education into a practical use for math! Why not ask them to convert dollars to euros to koruna to forints to dollars? That would give them a practical lesson in the math, plus the difference between buy/sell rates (and why you don't want to leave CZ with any korunas).
I doubt if euros will be accepted in Brno.

I was also in Prague in October. You will need korunas. Some shops do post prices in euros most places do not. It's a bit like Americans coming to Canada. Sure they can spend US$ in some places if they want to but they should not expect to get the best exchange rate.

You can also use the term "crown" for the Czech currency and you will BE completely understood. Save the Euros for other countries.

Thanks everyone. Unless someone else has more information, I think the answer is evident. I will likely have more questions as our date approaches.