In a large pot, combine the chopped rhubarb, sugar, ground cinnamon, lemon juice, and water. Stir well to combine all ingredients.

Let the mixture sit for 30 minutes to allow the rhubarb to release its juices and the sugar to dissolve.

After 30 minutes, bring the mixture to a boil over medium heat, stirring frequently to prevent sticking.

Once the mixture reaches a rolling boil, add the fruit pectin. Continue boiling for 1-2 minutes, stirring constantly, until the mixture thickens.

Remove the pot from heat and ladle the hot jam into sterilized jars, leaving a little space at the top.

Seal the jars tightly and let them cool to room temperature before storing in the refrigerator.