Chemistry- Blueberry Plum Jam

So a few days ago we went to the blueberry patch, check out our adventure here, and today we are processing our blueberries. We washed all the blueberries and laid them onto cookie sheets covered with paper towels to dry. Half of the blueberries we froze and the other half will be divided to make jam, muffins and just to eat (in my belly).

Making jam is a great experience for kids to see how solid can turn into liquid then back into solid just by changing the temperature. I remember making strawberry jam with my mom as a kid and would love for my kids to have the same fond memory.

Fun Facts:

Did you know? The boiling point of sugar is 320 degree Fahrenheit and water is 212 degrees Fahrenheit.

Since this is only the second time I’ve made jam without my mother, I needed to follow a recipe. I don’t store pectin at my house so I found a recipe for plum and blueberries because plums and apple jams don’t require pectin. To learn more about pectin and where it came from, check out this website. It has an article about Science and Magic of Jam Making.

I loosely followed a recipe by TallCloverFarm. Check out her recipe here. I say loosely because she recommends using 2 limes and I only had lemons. Plus I didn’t follow her instructions.

Before you get started, I recommend bringing out another activity that the kids can do while they wait for the jam to solidify. It takes almost a hour of stirring constantly so be prepared to hang in the kitchen a while.


  • 2 pounds of plum (about 4 cups)
  • 2 pounds of blueberries (about 6 cups)
  • 3 cups of sugar
  • 1 large lemon
  • I asked Alexa how many cups were in a pound.
  • Alexa responded that she is unable to help me because pounds is measured in mass and cups in measured in volume.

  • Then I thought what a great example for the kids. We have a small scale that allowed the kids see the weight of plums is different than the weight of blueberries. Then we tried sugar and lemons too. Fun little side experiment.
  • Start by combining plums, sugar and blueberries in a large pot on low heat. I crush the plums with my spoon as I stir it around. Once it is combined, I squeeze a lemon into my mixture.

    You will notice the berries starting to disappear into the liquid.

    Once all the blueberries have dissolved into the jam you are ready to remove it from the heat and let it cool. After about 30 minutes, we made peanut butter and jam sandwiches with our new plum-blueberry jam and everyone enjoyed them.

    Tall Clover Farm had a picture of jam scrambled into the shape of a heart. I thought I’d try and pay tribute to her.

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