In a 1.5 quart glass or earthenware dish, mix together the yeast and water until yeast is thoroughly dissolved
Add flour and mix until there are no lumps
Cover with a tea towel and store in a draft-free place for 48 hours, stirring a couple of times along the way (mixture will get a little foamy and bubbles will form, but it won’t expand much or increase in size at all. There may be some clear liquid that separates out, and you can just stir that back in; unless it’s pink (dead yeast), that’s okay. If the liquid is pink, yeah, your yeast is pooched and you need to start over)
After 2 days, you can store this in the fridge and draw off this ‘sponge’ as necessary for biscuits or bread. When you draw off from the ‘sponge’ for bread or biscuits, replace with equal parts flour and water to equal the amount you’ve drawn off. Leave this in a warm, still place for 24 hrs to get the sponge working again and it can once again go back in the fridge.