Homemade Strawberry Jam

***NOTE: The recipe below makes 3 batches of jam resulting in 12 pint sized jars. Each batch needs to be made individually. If you try and double the recipe the jam will have a hard time setting up. Best to just do each batch at a time. ***

Time: 2-3 hours
Yield: 12 pints
Recipe from Sure Jell with a few great tips from my Grandma Barb

12 jars
12 new lids
12 rings
8 pounds strawberries
3 (1.75 ounce) boxes Sure Jell pectin
21 C sugar 
large mouthed funnel
water bath canner

1. Wash all of your jars in hot soapy water.
2. Pour about 2 and 1/2 pounds strawberries into a colander and wash them with cold water.
3. Slice the green tops from the strawberries.
4. Place them in a blender and blend away, baby. You want all of the strawberries to be crushed. You don't need the mixture to be super smooth. You will need 5 cups crushed berries.
5. Measure 7 cups of sugar into a medium-sized bowl. It really helps to measure out the sugar before you get the berries on the stove. That way when you have a bubbling hot mixture on your hands you aren't trying to deal with a heavy bag of sugar as well.
6. Pour the crushed berries into a large heavy pot.
7. Grab 1 box of Sure Jell. Sprinkle  it over the crushed berries.
8. Add 1/2 teaspoon butter. This will help keep the jam from foaming up while it cooks.Give everything a nice stir. It will look a little bit clumpy at first. No worry there. Just stir it around until it's well combined.
9. Turn the heat to high and stir it constantly. You want it to reach a rolling boil, which means it continues to bubble up even while you are stirring. Once you have achieved a rolling boil, pour the sugar in. Now...do not panic at the amount of sugar here. Remember this will make 4 jars of jam and a serving size is super small.
10. Stir the sugar in and bring the mixture back to a rolling boil while you stir constantly. Let it boil for 1 minute and then remove it from the heat. Now, a word of caution here. Don't let the bubbling pot get out of control. It should bubble nicely for you, but if it's spitting jam all over and bubbling clear to the top of your large pot then turn the heat down. Sometimes I turn the burner off once I reach the rolling boil so it won't get too hot. Just watch it carefully and use your best judgement according to how hot your stove top is. Keep the boiling in control. :)
11. Grab your wide-mouthed funnel and place it on the top of a jar.
12. Pour the hot jam into the jar leaving about 1/2 inch of space between the top of the jar and the jam.
13. Take a damp paper towel and wipe the rim of the jar. You want to be sure it's free from any sticky jam so the lid can seal properly.
Just a word about lids and rings. You can reuse the rings, but you will want to be sure and purchase new lids for your jam. Your jars won't  seal properly if you use old lids. 
14. Place a new lid on the jar and screw a ring over the top. This batch will produce 4 pint-sized jars for you. Repeat steps 1-14 to make the additional batches
15. In order to be sure that your jars seal completely, pour warm water into your water bath canner. Carefully place the jars of jam on the rack and lower it into the water. The water should come at least 1 inch above the jars. Bring the water to a boil, place the lid on and let them process (with the water boiling) for 25 minutes. 
16. Carefully remove the jars from the water bath and allow them to cool on the counter. The lids will make a popping sound when they have sealed. You can test them by pressing your finger in the middle of the lid. If it's firm, they have sealed and you are good to go. If the lid gives a bit, then they haven't sealed and need to be processed longer in the water bath. 

Store your jars in a dark cool place.