Prepare boiling water canner. Heat jars in simmering water for at least ten minutes or until ready to use, don't boil. Wash lids and bands in warm soapy water and set aside. Wash strawberries, remove skins, and place in a wide heavy bottomed saucepan. Using a potato masher, gently break down the berries.

Combine strawberries and lemon juice in saucepan. Gradually stir in pectin. Bring mixture to a full rolling boil, stirring frequently until it thickens and begins to gell, about 15 to 20 minutes.

Ladle hot jam through a funnel and into jar leaving a 1/4 inch headspace. Wipe jar rim. Center lid on jar and apply band, adjust to fingertip tight. Place jar in boiling water canner. Repeat until all jars are filled.

Process (boil) jars for 10 minutes. Turn off heat, remove lid, let jars stand 5 minutes. Remove jars and allow to cool 12-24 hours. Check lids for seal, they should not flex when center is pressed.