Campfire Conundrum

UPDATE: March 20, 2017 - This digital breakout is currently inoperative because the PBS interactive about heat transfer has been taken down. I will try to reconfigure this breakout at some point in the future.

The best part of any sleepover at your cousin's house is making s'mores over a campfire in the backyard.

Your uncle got the fire started safely and you are ready to go.

Uh oh! Your aunt locked your ingredients in her lock box! She is a chemistry professor at the local college. Right now she's lecturing her students about heat transfer and is unreachable. Your uncle has no idea how to crack the three locks. 

The good news is your aunt always sets her locks based on her latest lecture. If you can learn about heat transfer before the fire dies down, you can enjoy s'mores. Good luck!