Science for Kids – Soda Bottle Compost

soda compost

My kids are nuts about science so we’re always looking for projects we can do at home that really allow them to get hands-on and see the things we are learning about. With spring weather teasing us around here, we’re thinking about planting a garden, so learning about how to create compost was a great place to start.

This simple kids science activity uses an empty 2 liter soda bottle and some things you have around your house and yard to teach kids about how compost is made. The clear soda bottle is perfect for keeping on eye on the changes that are happening within your compost and it’s a great way to recycle something that would have otherwise ended up in the trash.

Supplies Needed

  • Empty 2 Liter Soda Bottle
  • Soil
  • leaves, grass, newspaper, spoiled produce, and anything else you can find in your home or yard that can be composted


Cut the top off a 2 liter soda bottle and rinse it out well. Remove the label so that you can see everything inside the bottle well.

Start with a layer of soil on the bottom and alternate between soil and compostable material. You can use just about any plant matter. We had some peas that were getting mushy in our fridge so we threw those in with some dead leaves, grass, and pine cones. Shredded newspaper would have been great in here too.

Soda Bottle Compost

I set my 6 year old loose in the yard and had him look for anything that came from a plant. Older kids can alternate green matter and brown matter in their compost and experiment with different levels of moisture on the rate of decomposition.

Feel free to get emotionally attached to your compost bottle.

When your soda bottle has been filled, add water so it can start composting. You don’t want it to be sitting in water but you do want it to be damp all the way through.

Soda Bottle Compost

Let your compost sit for several weeks in a spot where it will get plenty of sun and won’t be tipped over.

What is a Hypothesis

Even young kids can be introduced to some basic science. After we were done creating our compost soda bottle, my kids and I talked about the scientific method and what a hypothesis is. Brain Pop is a great resource for explaining concepts to kids and they have a really fun video on the scientific method. It is a subscription service but they have a selection of free videos that rotates so you may get lucky, although it’s well worth the subscription.

Older kids can keep a scientific journal and write down their hypothesis and record observations as their compost pile changes. Younger kids can make a hypothesis about what will happen and keep an illustrated journal by drawing pictures of the changes they see happening.

Do you have a favorite science project you’ve done with your kids?

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