When we decided to put in a small garden pond I had planned on it being a fun hobby for the family that would also make a nice extra feature for the yard. As soon as I started to research it some to see how to go about it, it became obvious that it was going to be far more than a hobby to pass a few hours of quality time but would provide a virtual laboratory full of science and environmental project as well. It is my favorite type of learning with the children – hands on with actual results instead of fill in the block answers.
The Big Lessons
There are a lot of broad topic areas you can cover with a pond in your yard and countless small experiments but there are some really broad topic areas that apply to any water environment and on some scale to the environment in general. The first real lesson anybody needs to learn is about how the nitrogen cycle works in a contained water system (actually in any body of water but contained areas like small ponds and aquariums amplify the effects exponentially so it can be easily measured with basic aquarium test kits or science kits.
The nitrogen cycle is how wastes are broken down in the water, converted to nitrogen and ammonia, then the ammonia broken down by bacteria to naturally remove the toxins and maintain a safe environment for fish and amphibians living in the water. It is also a great way to teach the children about patience as they are all excites about getting fish and inhabitants for the pond and must continually check the nitrogen and ammonia levels for a week or more until it is balanced enough for the fish to live.
Failure to wait the required time will have unfortunate and dire results as the fish will die due to something referred to as new tank syndrome- but actually simply means there are not enough of the needed bacteria to convert the ammonia into a safer form. This also provides an opportunity to remind that bacteria, while bad in some cases- are essential for living things from people to fish to aid in digestion and handling of wastes. The same bacteria you are cultivating in the stony bottom of your pond are the ones used in much larger scales in waste water treatment plants.
Natural Environmental Balance is my favorite discussion we had about the pond as it applies to the whole world around us and all the smaller ecosystems that make up nature. In this we used fish to keep mosquito larvae from overtaking the pond, the tadpoles from frogs to eat the algae, and the insects that fed the frogs that laid eggs for tadpoles as examples.
If there were no fish then the insect larvae would quickly overtake the pond and without tadpoles the green slime algae would quickly coat the rocks and spaces between the rocks that the bacteria for breaking down waste needs to grow and without insects the frogs would leave and there would be no tadpoles etc., etc., until it was clear that the only way to maintain the pond is by seeking a balance for all and eliminating any single piece of the puzzle would result in loss of all. Our goal was to try to make it a self-sufficient eco-system with minimal artificial filtration and no chemical usage. Due to the smallish size, a pond pump for water circulation and aeration is needed in any artificial system.
With small ponds like ours (approximately 175 gallons of water) changes in all things happen very quickly. Within 2 or 3 days algae will fill a pond if there is too much waste being added to the water resulting in too many nitrates (common from overfeeding). Observing the pond and making a prediction of the results of chemical tests based on observation of the environment was the best part and teaches them to look at things they see in the world around them and predict the causes or to see issues like pollution and predict the results.
The Smaller but Important Lessons
After all the gee whiz science experiments and talk of maintaining balance in the environment there are so many small lessons to be learned you could have a calendar filled easily. Identifying the insects around the pond, name the birds seen near the pond, taking temperature readings of the pond and charting them for math and science lessons are just a few. Whether a pond is used as part of a homeschooling curriculum like many are, or as supplemental learning and valuable time together as was our case, it provides educational opportunities galore in something both I and my children enjoy doing together.