If you're making jam in small jars (1 or 2 ounces) it's best to work with a partner; one person to pour the jam into the jars, the other person to clean the rims and seal. This recipe makes approximately 80-90 ounces of jam, so you will need about 80-90 one-ounce jars, or 48 two-ounce jars, or 24 four-ounce jars.
In a pan, cover screw caps with water and simmer for 10 minutes. Wash jars and keep immersed in simmering water for at least ten minutes until ready to fill. Measure sugar into a bowl, set aside. Stir pectin powder into the mashed berries in cook pot and bring to a full rolling boil (a boil that cannot be stirred down), stirring constantly. Be sure you have a large pot, as the mixture will boil up very high. Add sugar, stir constantly until it returns to a full rolling boil. Continue to stir and cook at full rolling boil for exactly 4 minutes. Take off heat and immediately pour into hot jars, fill to within 3/8" of the top. Wipe jar rims with a clean, damp paper towel. Immediately put lids on and screw down tightly. Turn jars upside down, then turn upright after 5 minutes. When cool, rinse off any jam residue with cool water.