RPlace rhubarb and sugar in a large saucepan and stir to combine. Let sit for 15 minutes, stirring often.
Place the rhubarb mixture on a burner at medium heat. Bring the mixture to a full boil. Turn the the burner down to medium low heat and continue to cook until rhubarb is soft.
Combine strawberries with the rhubarb mixture and cook until it begins to thicken, stirring often.
Remove the hot jam mixture from the heat and stir in the gelatin; set aside to cool, or immediately pack in hot jars. Cool to room temperature. Once jam cools, what you won't be using soon in the freezer.