How can you tell if yeast is still active?

Question

I want to bake bread, and the kind I'm making requires yeast, which I have, but it's kind of old and I'm not sure if it's still active. How can I check to see if it's still active without using up my ingredients for the bread? I don't want to make a test batch.

Answer 1

put some in warm water with a pinch of sugar,wait 10 min, if it foams, your in