use up any soft fruit
Basically put your normal jam ingredients into the biggest bowl/casserole you can find. A six pint is the best. This is because the jam will bubble up and it needs space to do this without boiling over. Cook uncovered fro 15 minutes, test and repeat in 2 minute increments until it is done. The easiest way to test (if you don't have a jam thermometer) is to put a saucer in the freezer and when you want to test the jam, whip out quickly and put a small bit of jam on it and push it around until its cold and see if it looks thick enough to be called jam (this is called testing for set).
Strawberry: 2 cups slightly crushed berries, 1 1/2 cups sugar, 1/2 teaspoon butter, 1 1/2 tablespoons lemon juice
Raspberry: the same but only 1 tablespoon lemon juice
Blueberry: the same but 1/4 cup lemon juice and 1/2 teaspoon grated lemon peel
Plum: 1 lb plums makes about the 2 cups of chopped fruit needed, 1 1/2 cups sugar, 1/2 teaspoon butter, 1 1/2 tablespoons lemon juice