Clean jars and lids with warm soapy water. Ensure the jars do not have any chips or bubbles in the glass.
Put your water bath canner on your stove. Add your canning rack to your water bath canner. Add your half-pint jars to the water bath canner. They will warm as you heat the water. Add enough water to cover jars with at least 2-3 inches of water. Turn on the stove to medium heat.
Add lemon juice to a stainless steel pot. As you are chopping your pears add them to the lemon juice in the stainless steel pot to prevent the pear pieces from darkening. Add all pears
Move the stainless steel pot to the stove. Add Sugar and Cinnamon to the pot.
Over high heat, stirring constantly, bring the contents to a full rolling boil that can't be stirred down.
Stir in pectin. Boil hard, stirring constantly, for 1 minute.
Remove from heat and skim off foam from the top of the jam.
Remove 1 jar at a time from the water bath canner with your jar lifter.
Ladle hot jam into hot jars, leaving 1/4 inch headspace (Check with headspace measurer). Remove air bubbles with a de-bubbler and adjust the headspace by adding more hot jam if necessary.
Wipe the rim to ensure a good seal is made with the lid. Center the lid on the jar and screw the band down to fingertip tight.
Place the jar in the canner using your jar lifter. Repeat steps 9-10 until all jam is used. Make sure the jars are completely covered by 2-3 inches of water.
If your water is not boiling start your processing time when the water is boiling. Process half-pint jars for 10 minutes (make sure to adjust for your altitude). Set a timer, it makes it much easier to make sure you process for the correct time. When your timer goes off turn off the heat and remove the canner lid. Leave the jars in the water for 5 minutes.
Lift your canning rack out of the water. Using your jar lifer carefully move the jars onto a wire rack or kitchen towel to allow them to cool. When moving the jars try not to tilt them to the side as this could affect the seal of the jars. Allow your jars to cool for 12-24 hours before handling.
Once cool, remove the canning rings from the jars. Wash your jars off to ensure no food residue on the outside of the jar from processing. Label your jar with the name of the recipe and date. This will help you remember what recipe you used to can and the date will allow you to use the oldest canned goods first.