Wash the strawberries.
Fill canning pot with water and place on stove. Be sure there is a rack or something to elevate the jars so they don't touch the bottom of the pan. Start heating water to a boil.
Ready canning jars, ladle and funnel.
Measure 4 cups of sugar and place into a bowl. Set aside.
In another bowl, place pectin and a 1/4 cup of the measured sugar.
Cut off the tops and quarter strawberries. Place quartered strawberries into a saucepan.
Mash strawberries using a potato masher to desired consistency.
Mix pectin and sugar mixture into the mashed strawberries. Add a pat of butter (about 1 Tbsp) to reduce foaming, if desired. Heat, stirring often, to a boil.
Once at a rolling boil, add the sugar, stirring constantly until dissolved. Let boil for 1 minute.
Skim off foam. Ladle hot jam into canning jars, leaving 1/4 inch of headspace.
Using a damp cloth or paper towel, wipe the rim of each jar.
Place lids onto jars, and hand tighten rings.
Use the tongs to place jars into the boiling water in the pot (or canner). Allow to boil for 5 minutes.
Remove jars using tongs and allow to cool and set for 24 hours. After 24 hours have passed, make sure jars are sealed. Check by pressing the center of each lid. If there is no give, they are properly sealed.
Yield is eight 8oz jars of jam! Jars can remain on the shelf for 1 to 2 years. Always check for spoilage. Once opened, it should be refrigerated and will last about 4 weeks.