In a large pot (it will bubble up as it cooks) stir together the fruit, pectin, sugar and lemon juice. Bring to a full boil and cook, stirring often, for about 20 minutes, or until a small spoonful set on a small dish you've stashed in the fridge or freezer gels enough that your finger leaves a trail when you run it through the puddle of jam.
Ladle into clean, hot jars, wipe rims and seal according to the jar manufacturer's directions (I use the snap lid jars). Set aside to cool. Refrigerate any that don't seal properly.
Our batch made almost ten 250 mL jars.