Experiments for Spooky Science: Gooey Osmosis

Oct 15, 2023 | Articles, At Home Learning Tips, Just For Parents, Mass Appeal, STEM

October is a great time of year to put on your Dr. Frankenstein lab coat and mix up spooky potions for some spooky science!

Part 1 of 4 experiments for Spooky Science: Gooey Osmosis

By Nicole Rhodes, the lead STEAM tutor at The Community Classroom

Halloween is one of my favorite holidays because it’s a wonderful excuse to be both silly and explore things that are a little gross–gooey, rotten, and stinky things are all a part of the fun! I love experimenting with things you can find around the house, especially things that might otherwise go to waste. I’m talking about half-rotten apples, candy at the bottom of the trick-or-treat bag, and pantry staples. All of the following experiments can be fun for both toddlers and older kids (adults too!). The scientific principles can meet kids where they are – the level has to do with the complexity of the language used. For example, we could be “seeing where the water moves” or “exploring hypertonic and hypotonic solutions” while doing the same experiment! 

The following four experiments are great for open-ended questions while exploring topics in STEAM. Candy Osmosis demonstrates a biochemical process that our cells do every day. Building Apple Skull Volcanoes involves the chemistry of acids and bases, with an optional add-on of enzymes in decaying apples. Watching fake plastic spiders hover and jump in the Spider Lava Lamp investigates the density of liquids and another chemical reaction to produce carbon dioxide bubbles. Finally, adding play-dough muscles to Halloween skeleton decorations is a great hands-on way to visualize human anatomy in the Halloween Skeleton Anatomy activity. 

  • Candy Osmosis
  • Apple Skull Volcanos 
  • Spider Lava Lamp
  • Halloween Skeleton Anatomy

Spooky Science Experiment 1: Candy Osmosis

The first experiment is one of my biology classroom favorites, but can be easily adapted to do with young kids. My 4-year-old was my helper on this one! We explored the concept of osmosis using gummy worms. 

To prepare for the experiment, you will need three clear jars, at least three of the same size gummy candies, water, and sugar syrup. I’ve used Karo Syrup with success in the past, but I did not have any on hand, so I put 1 cup of sugar in a heat-proof jar and added just enough boiling water to make the sugar dissolve (about 3 tablespoons)–obviously, adults should do this part! You are making a super concentrated HYPERTONIC solution, which means that you have a higher concentration of solids (like salt or sugar) than the gummy candy. Next, you fill a second jar with plain tap water, which is the HYPOTONIC solution, meaning that you have a lower

concentration of solids than the gummy. Place a gummy in each jar and let it sit for several hours or overnight. The next day, you should see a difference in the gummies’ sizes!


  • 3 Clear jars
  • 6 Gummy candies
  • Water 
  • Corn syrup or Sugar syrup


    1. Fill one jar with water, the second with corn syrup, and leave the third empty.
    2. Measure the gummies with a ruler, or trace the outline on a piece of paper.


  1. Place 2 gummies in each jar, and make a prediction for what will happen.
  2. Cover jars and let them sit for at least 5 hours or overnight. 
  3. Take the gummies out and measure/trace them again. How did they change? Why?

Why do the gummies in the concentrated sugar solution shrink? Why do gummies grow in pure water? It’s all about OSMOSIS! Gummy candies are mostly made of sugar and gelatin. Sugar on its own would just dissolve in water, but the presence of gelatin gives it structure. All things in nature aim to achieve homeostasis, or equilibrium. For example, if you spray an air freshener in one corner of a room, those molecules will eventually distribute evenly to fill the room with equal space between each molecule of air freshener. When you put the gummy in pure water, the concentration of particles (sugar) is higher in the gummy, but the sugar molecules are stuck in the gelatin matrix. To achieve equilibrium, water actually moves into the gummy, making it “grow.”

Conversely, if you place a gummy in a liquid with a higher concentration of particles, water should actually move out of the gummy. This did not make as striking a difference in our experiment, since the gummy was a little dry to begin with. We could have moved the water-soaked large gummy into the sugar syrup and watched it shrink. To describe this to a preschooler, I said that “The water moves where there is no water.” We also used number sense and paper tracing to measure the gummies before and after soaking to quantify their change in size. I put the soaked gummies on a paper towel before placing them on the paper to trace them again. Our gummy worms were a little floppy for this experiment, and I would recommend a shorter/rounder candy.

Want more? This is part 1 of 4. You can also find:


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