Crush strawberries and measure 4-1/2 cups berries into a large saucepan. Stir in pectin and bring to a rolling boil over high heat, stirring frequently. Add sugar and return to a rolling boil. Boil for 1 minute, stirring constantly. , Remove from heat; skim off foam. Ladle hot mixture into hot half-pint jars, leaving 1/4-in. headspace. Remove air bubbles and adjust headspace, if necessary, by adding hot mixture. Wipe rims. Center lids on jars; screw on bands until fingertip tight. Place jars into a canner with simmering water, ensuring that they are completely covered with water. Bring to a boil; process for 10 minutes. Remove jars and cool.