Making up a Wyeast Starter

The expanded "smacked" pack

Opening with sterilised scissors

Carefully pouring out the active yeast

..and adding to 1/2 gall of boiled, cooled wort

The starter just after pitching

And after 24 hours

After it's almost fermented out, the starter is split into six small bottles.

The yeast must be kept refrigerated or it won't keep for more than a couple of weeks.