This is just a little worksheet that I use in a General Chemistry course to teach Gibbs Free Energy calculations and the idea of a coupled reaction, while foreshadowing ideas from metallurgy and electrochemistry (sacrificial reductants, entropy-driven smelting, fuels as reductants) for the end of the course when I generally address these.
Pens and/or pencils
At this point, I have generally discussed Gibbs Free Energy and explained how to calculate Gibbs Free Energy, Enthalpy, and Entropy of Reactions by using tabulated values for absolute entropies and Heats and Free Energies of Formation. This gives them a little practice at it, and shows some of the pitfalls (you can only use Delta Gf when you're at 25C, if your enthalpy is negative and entropy positive, there is no temperature at which the reaction becomes non-spontaneous, etc.)
They often forget to use coefficients in their calculations, for which this is a good reminder.