Third day of summer camp~ Finally the first day of experimenting with the kids.

Plastic pollution is one of my more *passionate* global issues, and I’ve done numerous major projects related to raising awareness about this issue in previous years. Though not directly related to plastic pollution, I’m also planning to start an Advanced Topic project on low carbon diets and raising public awareness of the significance of implementing such diets.

As an initiative, I wanted to teach the kids about the current issue of microplastics, which are microparticles of the plastic waste that have degraded into smaller pieces over the years. When I told the kids that we eventually eat and have microplastics in our bodily systems due to the food chain cycle, I heard countless gasps in the room, and so it was quite entertaining to see how shocked they were.

So, for today’s class, we made Oohos (edible water bottles)! These water bottles are edible, so they have a jelly-like membrane that encloses the water inside.

Here are the materials:

• 4 g sodium alginate
• 8 g calcium lactate
• 2 bowls
• Deep spoon (eg ladle, soup spoon)
• Slotted spoon
• Immersion blender

I didn’t know sodium alginate smelled this terrible. It kind of reminds me of a fish tank? It also kind of smelled like a public bathroom but with the mix of some sterile smell. Anyways, the purpose of this experiment was to teach students about the importance of reducing plastic waste by creating biodegradable and edible water bottles.

The kids began writing their journal entries, which they decorated yesterday.

Here are the steps to creating oohos:

1. Measure 4 g of sodium alginate and 8g of calcium lactate.
2. In a small bowl, add 4 gram of sodium alginate to 500ml of water.
3. Use the hand mixer dissolve the sodium alginate in the water.Let the mixture sit for about 15 minutes to remove any air bubbles. The mixture will turn from a white liquid to a clear mixture.
4. In a large bowl, stir 4 grams of calcium lactate into 1L of water. Mix well to dissolve the calcium lactate.
5. Use your rounded spoon to scoop up the sodium alginate solution.
6. Gently drop the sodium alginate solution into the bowl containing the calcium lactate solution. Be careful the water balls don’t touch each other because they would stick together. Let the water balls sit in the calcium lactate solution for 3 minutes. You can gently stir around the calcium lactate solution if you like. (Note: the time determines the thickness of the polymer coating. Use less time for a thinner coating and more time for a thicker coating.)
7. Use a slotted spoon to gently remove each water ball. Place each ball in a bowl of water to stop any further reaction. Now you can remove the edible water bottles and drink them. The inside of each ball is water. The bottle is edible too—it’s an algae-based polymer.

*This recipe was referenced from Inhabitat.com and Seodam’s Youtube video.

The calcium lactate didn’t take much time to dissolve, even when we used a hand whisk. However, the sodium lactate did take a lot of time to dissolve, and it wouldn’t really dissolve very well, despite using a hand mixer (the electrically powered ones). So we just blended it into fine particles, but it still wasn’t fully dissolved.

While we waited for 15 minutes, the kids were instructed to write their journal entries about their hypotheses and the material list. Interestingly, the solution did turn a bit white and thickened.

The kids collaborated with each other, taking turns to measure the ingredients, blend them, and scooping their own water bottles.

Here are some photos:

Also, when I told the kids that these were edible, they all tried drinking from them, but apparently they tasted terrible. The kids were hysterically running around the sinks, spitting out the liquids they sucked up and gargling their mouths. I would highly recommend other teachers to use strongly flavored drinks/drinks with a strong fragrance. Also, it would’ve been interesting to use food coloring to see the differently colored oohos.

– Joanna Kim, June 17th, 2022, 1:48AM KST –