Wash and prepare glass or plastic containers to store jam in. You can buy these or I have found that old sour cream containers work just fine. Next, crush your berries using a potato masher or food processor. I know the instuctions inside the package say not the puree but I alsways have with my rapberry jam and it has always worked. Measure your sugar into a bowl. Measure your berries and put into a seperate large bowl. Add the lemon juice to the berries. Gradually stir in the box of MCP Pectin. Set aside for 30 minutes, stirring every 5 minutes to dissolve the pectin thoroughly. Next, stir in corn syrup. This prevents sugar crystals during freezer storage. Gradually stir in the sugar. Stir until the sugar is dissolved and no longer grainy. Pour into prepared containers leaving 1/2 inch at top for expansion during freezing. Cover with lids. Let stand at room temperature for 24 hours. Then store in freezer for up to 1 year. Thaw in refrigerator. Refrigerate up to 3 weeks (I’ve done mine longer).