Sort and wash fully ripe strawberries; Remove stems and caps. Crush berries. Measure crushed strawberries into a kettle. Add pectin and stir well. Place on high heat and stirring constantly, bring quickly to a full boil with bubbles over the entire surface. Add sugar, continue stirring, and heat again to a full bubbling boil. Boil hard for 1 minute, stirring constantly. Remove from heat; skim. Fill and seal containers. Process 5 minutes in boiling water bath.