My students’ favorite lab is building and taking care of Ecocolumns. This lab gives them practice in long-term data collection and a myriad of other essential topics in APES. Here are the posts you can click on to learn how to build, buy supplies and assess ecocolumns.
No matter how well an ecocolumn is built, some columns will have issues. Fish die, plants, die, fish disappear (yes, they do), plants disappear. Weird plants grow, bugs infect, they’re dropped, etc. Its all OK. Its part of learning and discovering and as teachers, sometimes we have to say we don’t know either and leave it at that. Read about some things they will learn, however, through ecocolumns.
Ecocolumns can teach the kids A LOT of scientific concepts if you are purposeful with the learning. If not, the kids just enjoy growing plants and having a fish and this is not worth the class time it takes.
Make sure you take the time to lecture or allow for inquiry discussions about the scientific processes in an ecocolumns. Students can take observations and make inferences, but you will need to teach them about some of the indirect processes going on (such as nutrient cycling).
Data collection, graphing and analysis. The more the kids take data and see patterns over time, the better the kids are able to answer these types questions on the AP® Exam. The AP® Exam is 2/3 higher level thinking and will have data-set analysis. In order to give my students more lab time, I flip my class.
Nutrient Cycling. Direct kids to see how the nitrogen cycle, carbon cycle, phosphorus cycle and water cycle are implemented in the ecocolumn. Kids really can’t figure this out on their own through inquiry so its best to have direct instruction in this (even though I’m a huge inquiry fan). Dead fish provide a great learning opportunity if you bury it in the soil.
Nitrogen Cycle. Big emphasis on this cycle which is hugely important in this class and on the AP® Exam. Nitrogen fixation with the legumes, fish waste (ammonification) and then nitrification with beneficial bacteria.
Limiting Factors. Plants will soon run out of space and decline. Fish could run out of dissolved oxygen if they’re too big for the chamber or if the kids put in too many.
Decomposition and Detritivores and Leaf Litter. I favor a filter chamber instead of a decomposition chamber, but we add worms and other detritivores to the terrestrial chamber to teach them about decomposition. My students don’t live in a forest (we live in Chaparral) so they don’t know about leaf litter–this is how they learn.
Water treatment and wastewater treatment. The filter chamber mimics one step in water treatment and is also tertiary wastewater treatment.
Food Web. Elodea or duckweed eaten by the fish. Pests that find the ecocolumn and eat the plants.
Water Quality: Temperature, pH, Dissolved Oxygen, Nitriates. Students will see how they change (or don’t change) over time and may begin to see patterns.
Soil Quality: Temperature, pH, fertility (NPK). Kids can see how soil quality changes (or doesn’t change) over time. You will need to guide them to why each test is important. They can also learn about soil structure, leaching, tannins, drainage etc.
Eutrophication and BOD. If you have a dissolved oxygen probe or test kit (I highly recommend buying a dissolved oxygen probe if you have some funds). This is a common topic on the AP® exam and there is no better way for students to understand BOD (Biological Oxygen Demand), eutrophication and other issues than to measure DO over time. I like the Milwaukee MW600 LED Economy Portable Dissolved Oxygen Meter.
Sometimes new teachers panic when they see all the shiny probes, grow lights and data measuring stuff that veteran teachers have. Don’t worry…most of us started out with limited supplies also. Ecocolumns can be done cheaply or expensively. Most teachers start off cheaply and the kids still learn a ton and have lots of fun.
Water plants: If you have a pond nearby, go collect some duckweed or other water plants. If not, buy elodea (called anachris) at the pet store and break the stems in half or thirds. Elodea doesn’t care and will grow.
My son collecting duckweed.
Fish: Feeder fish that are $0.10 are notoriously bad for ecocolumns, sorry. Try getting a donation of fish. I have received Gambusia from the county health department. Ask around if someone has a pond where the fish have been overbreeding. If you have to get feeder fish, minnows/rosy reds, are better than goldfish. Or, forget fish and get small snails. The pet store will often donate as snails are pests in their tanks, but they’re awesome for us. Or, collect critters from a local pond.
Fish Tanks: Ask your kids to donate an old one that’s getting dusty in their attic or garage. I’ve never purchased a fish tank-they’ve all been donations from people wanting to get rid of them.
Windows: Use to grow plants instead of plant lights.
Plant light donation: Ask your local law enforcement for a donation of confiscated grow lights from a busted marijuana operation. My colleague, Danielle Werts, did that. Be prepared for drug dogs to go crazy, however, if they come through your school.
Bugs: Go on a bug hunt at school or kids collect worms and detritivores on their own and bring in.
Cheap Data for Ecocolumns
You don’t have to take every piece of data mentioned here. Only take the data that you have equipment for.
Rulers: Measure plant height, elodea length etc.
Thermometers: Most labs have these already and you can use to measure water temperature and soil temperature.
pH strips to measure pH of water in lieu of pH meters. (pH meters are pretty cheap, however, on Amazon).
Observations: The kids can learn a lot with basic observations.
A little Money
Build your own plant lights: So much cheaper than buying a set from a scientific supply company. PVC pipe and shop lights will cost less than $50. My colleague, Laura Solarez, had her husband build her a set over last summer. You can also ask the wood shop teacher (if you have one) or a parent to build if you buy the supplies.
Nitrate Test Strips: Use a few times during the lab depending on your budget. They’re about $18-20 for a bottle of 50, but wait! I found out last year from some smart teachers that you can slice in half and increase to 100 per bottle! You use one strip per ecocolumn and you don’t have to take nitrate data every time. These strips have served me well for years Industrial Test Systems 480009 WaterWorks Nitrate/Nitrite Nitrogen
This picture shows a whole strip, but now I have student service cut in half for me length-wise to double the amount of strips.
Dissolved oxygen kit: $40-60. This is an important reading which helps kids really understand aquatic ecosystems. For large classes over multiple years, a probe is more economical, but to start, you can go with a kit.
Soil Probes or Soil Testing Kit: $25 on Amazon. Kids can pass probes and kits around so you can start with one or two and then build up supplies over time.
Expensive Supplies to Buy Over Time (or if you are blessed with an awesome budget)
Dissolved Oxygen Probe/s: The most important item to splurge on when you get some money. Kids really see patterns and changes regarding DO and this is a topic that is a big part of our exam. I rotated 1 probe around to different groups when I first started, then built up my supply to 3 probes between 9 groups and now I’m up to 5 probes to rotate between 9 groups. Again, this took several years to get this many. I like the Milwaukee MW600 LED Economy Portable Dissolved Oxygen Meter, because they last a long time and rarely need calibration.
Grow Lights: If you have some money, the pre-made grow lights are nice. They come with trays and a cover for humidity.
Fish Tanks, Filters and Food to keep a breeding stock of fish.
Gambusia (mosquito fish) are my favorite and I keep them year-round in 3 aquariums.
Buy more probes so not as many groups have to share. It will speed up the data process. I now have one soil probe per group and one pH, temperature, and DO probe per two groups. Data takes 10-15 min a week this way.
Draining the ecocolumn once every day or two is extremely important to prevent fish death. Potting soil contains silt and sand contains dust-both of which will clog fish gills. The more you drain, the cleaner the water becomes as you flush these particles out. The water may still be slightly orange/brown after two weeks, but this is mainly due to tannins in the soil rather than silt.
I usually send one student from each group into the lab to empty out the old water and fill the ecocolumn from the top to drain until the next day. This takes about 5 minutes.
Build the Aquatic Chamber
This is a fairly easy chamber to build. Also have students continue to take other data–plant height, soil measurements (optional).
I have a video on how to build the aquatic chamber or just keep scrolling down to the pictures and explanation.
First they need to clean some gravel. You can use aquarium gravel, but its really expensive. We use construction gravel that costs $3.50 for 50 lbs. But, its filthy so kids have to clean it.
Next, students add purified water. I have kids “donate” the water from their original bottles in these buckets and keep for two weeks. Its not as good as distilled, but its better than me spending a week making liters and liters using our building’s distiller.
Students take water quality measurements (see below) and then add a sprig of elodea. They measure the length each time we do data. Elodea is the cheapest water plant at the pet store (called Anachris there). Its also available to order from scientific supply companies. Duckweed also works well, but I don’t often have a steady supply here in Southern California.
Make sure students leave enough space for air to flow through and that there are holes cut in two sides. This will allow for enough dissolved oxygen and prevent fish death.
NO FISH FOR TWO MORE DAYS! Dust from the gravel needs to settle or it can kill the fish by clogging their gills and nitrifying bacteria need to colonize the water.
Taking Water Quality Measurements
First, use what you have. I’ve built up my collection of probes over 10 years using various grants. You won’t have this much to start and neither did I. Probe readings take only one minute so students can pass around and share.
Last year, I made laminated instruction sheets for each probe and then kicked myself for not thinking of the idea years ago.
You can also use water quality testing kits, regular thermometers, pH paper, etc. Splurge on a dissolved oxygen probe if you can beg some money.
I use vernier temperature probes, because I have them, but this is the expensive option. You could use a regular thermometer or temperature probe just as well and they’re cheaper.
I use pH probes from Amazon, because they’re pretty cheap–$15-$18 each. But, like most pH probes, they need calibration every week or so. I train a student lab assistant to calibrate. They can be broken if water gets in the electronics, but they’re cheap enough to replace if that happens. Pocket Size pH Meter Digital Water Quality Tester
We take group nitrate and nitrite data since the water is all from the same source. This saves money. After this day, the students will take their own readings using strips. I use strips instead of probes, because nitrate probes are notoriously difficult and lose calibration easily–sometimes in the middle of a period and take 30 min to calibrate. Forget it! I learned a new trick last year–slice the strips in half vertically and they last twice as long! A HUGE money saver!
These strips have served me well for years Industrial Test Systems 480009 WaterWorks Nitrate/Nitrite Nitrogen
Below is a video on how to use each of the probes and strips.
After two more days, your students will LOVE your class, because they get a fish!
After weeks of your students being excited about getting a fish, today is the day!
Word of caution–don’t add a fish for two weeks after building the initial column and for two days after building the aquatic chamber. Seriously–don’t do it. I did not heed the warnings myself the first time I built and had massive fish death. Your students will keep bugging you about fish, but teach them patience. The reasons why are found in my previous post-Building the Aquatic Chamber.
Let’s discuss some of the popular varieties of fish for ecocolumns. There are many bad choice and to be honest, I’ve used some or allowed students to buy and wish I knew this information. Shout out to Katy Sturges for some of the info on fish no-nos.
Goldfish: Cheap, but not good for ecocolumns. Their waste contains a large amount of ammonia which will burn their scales (black spots). They will also eat all of the elodea leaves quickly and kill it. You may need to replace the elodea or supplement with fish food.
Rosy Red Minnows: Feeder fish so they’re cheap like goldfish, but I’ve found that they have a high mortality rate. Since they’re so cheap, you can replace easily when they die (Dead fish teach a lot about nutrient cycling when students bury in their soil). Will sometimes eat a lot of elodea too.
Beta (Chinese Fighting Fish): Some people use in ecocolumns, because they can gulp air from the surface and will survive when dissolved oxygen levels are low. The problem, however, is that they are insectivores and will only eat the elodea if desperate. They need a supply of brine shrimp, zooplankton, daphnia, or mosquito larvae. If you use healthy pond water with these invertebrates, this might do the trick. The other problem is that they can see each other in adjacent ecocolumns which stresses them out. There are, however, creative ways to remedy the problems and use beta fish.
Guppies: A good choice, but can be pricey if you have a lot of columns. They can tolerate cold and dirty water and aren’t too large to use up the dissolved oxygen. Some of my students purchase these at the pet store.
Gambusia (Mosquito Fish): My favorite. My original population came from Los Angeles County Vector Control which donated a bunch. Vector Control uses these fish in abandoned pools or ponds to eat mosquitos and their larvae (hence the name). Can also be purchased from Carolina Biological, but they have a hefty price if you include the shipping cost. If you purchase some or get some donated, try to keep year-round. They will breed and keep your stock going. I have a super strong stock now as the weak ones have died off and the strong keep breeding. Natural selection at work! A draw-back to Gambusia is that they are omnivores and prefer to eat invertebrates. But, they will eat the elodea and survive in Ecocolumns for several weeks.
Tetra: I’ve heard good things about these fish from other teachers, but have never used myself. Can also tolerate cold, dirty water.
Snails: A good solution if you can’t find any healthy fish to add. Snails are often pests at the pet store and they will give them away to you. They will eat algae.
Take Water Quality Data First
Students should take water quality data first before adding a fish. They need to see what changed in their water after the elodea has been in the water for a couple of days. Students also should take other data–plant height, soil etc.
After taking water quality data, students can add a fish. Make sure the dissolved oxygen levels are higher than 3 mg/L before adding a fish. They should be if students cut some flap/air holes in the chamber.
Adding a Fish
As a rule of thumb, students can add up to two small fish (guppy-sized) or one medium-sized fish (1-2 inches). If they add more, they run the risk of killing them all due to dissolved oxygen depletion.
This is the last stage of building the ecocolumn. I try to have students take data again within a few days to see nitrates building up in the water and then weekly after that.
Students should take terrestrial chamber data today-before or after adding detritivores: Plant heights and observations. Soil data also if you have probes or kits (optional).
We add detritivores (insects that decompose) which allows students to learn more about nutrient cycling. NO herbivores as they will eat all the seedlings and plants. NO carnivores (spiders, lady bugs) as they won’t have any food and will crawl/fly away. NO crawling or flying insects as they will escape. (Believe me, you don’t want crickets chirping in your building) Initially, my students think the sprinkler top will keep the crawling bugs in, but I tell them we discard/recycle the sprinkler top soon as they plants need more room to grow.
You can take the kids on a bug hunt around campus or have them collect and bring from home. I tell kids to bring from home–go in their yards or the park and turn over rocks to find bugs and worms. I also tell them that if they’re SUPER WIMPY they can buy worms at Walmart (bait/fishing section) and mealworms at the pet store (not a worm, but beetle larvae).
The best detritivores are ones that are easily found are earthworms, pill-bugs/sowbugs/roly polys, pinscher bugs, and beetles. Be careful as some will find caterpillars which are super cool, but eat all the plants.
Side note: There is a way to add a non-venemous spider to your ecocolumns. You can have students add a piece of fruit to a chamber in order to attract fruit flies. When the flies arrive, you now have a food source for spiders. I don’t do this, but have heard its possible.
Providing Leaf Litter
Bugs need hiding places and food and leaf litter provides all that. My students go outside and collect a few green and brown leaves. They tear up and line the soil with leaf litter. They must be careful to avoid smothering seedlings. Its been a week since seeds were planted so most have germinated and grown at this point.
My students live in the Chaparral (well, technically in the suburbs surrounded by Chaparral), so many have never heard of “leaf litter” or know its function. This is a great opportunity for them to learn that in addition to hiding places and food for the detritivores, leaf litter prevents water loss, prevents erosion, and add nutrients to the soil.
From experience, I’ve found that students need help with the scientific concepts in ecocolumns. A lot of the concepts are inferred and cannot be directly observed (part of biogeochemical cycles, for example). Just making observations and having them research what’s going doesn’t lead them to the immense amount they can potentially learn. Scaffolding is important. I give notes and then refer to these concepts all the time. Students then have to process their notes, data and observations in more higher-level ways. The AP® Exam contains 2/3 higher level thinking questions so these skills are important.
To find time for these essential skills, I flipped my class last year and enjoy the time to build higher-level thinking in my students. Even with the time, after a few weeks of ecocolumns, I train my students to spend only 10 minutes taking data.
In an additional week, its time to build the aquatic chamber and add a fish.
On the second day of building ecocolumns, students add seeds and begin taking data. (This can be the second hour of a block period). Before they do this, however, they need to make sure their chambers are draining properly.
When the terrestrial chamber is draining properly, it is time to plant seeds. Its REALLY important to make sure they drain, drain, drain, several times as silt can clog up the drainage holes on the 5th draining or so. If the drainage gets clogged after they plant seeds in the soil, the soil and seeds get moved around (erosion) and buried too deep.
Students can choose 5 different seeds to plant. I make them choose 2 legumes out of the 5 in order to learn about nitrogen fixation.
Try to buy seeds that germinate quickly. Students get very concerned when some of their seeds germinate and others take 2 weeks. They think there’s something wrong. Although that too, is a good learning experience.
I show my students about 2 minutes of this video below to show them how to write on the bottles and plant the seeds.
I require my groups to rotate the duty of filling in the spreadsheet as we take weekly data. This makes sure all kids get practice using spreadsheets-an essential skill in many jobs.
TEACH them how to make a spreadsheet as most teens don’t know how. Scaffold, give templates, teach how to “wrap text”. Mine have always been very appreciative to learn this skill. Your template will include the specific tests that you have equipment for–probes, test strips, test kits, etc. The spreadsheet template I use is found on the student directions.
Students also need to be taught that when we don’t take data for a certain test, they should not enter “0” as this is a real quantity. They need to leave the box blank.
Soil data is not a necessity, but if you have some funds to buy some probes or soil test kits, it can be a good addition to ecocolumn data. Last year, I purchased several of these probes so my students now add soil temperature, pH, and combined NPK fertility. Again, don’t worry if you don’t do soil tests, I didn’t for the first 10 years of ecocolumns. Collect equipment over time.
Since my students now take soil data weekly, by the time we cover soil several chapters later, they have some familiarity with it and I can save time by not doing a chemistry of soil lab.
After planting seeds, students should only water using the “sprinkler” they made when they were cutting bottles. This will gently water the soil without causing erosion and displacement of seeds.
Let your plants grow for about a week. DON’T MAKE YOUR AQUATIC CHAMBER AND ADD FISH YET.
Students thoroughly enjoy building ecocolumns. Building usually takes 2 full class periods (50-55 min). The example here is of an an ecocolumn with three chambers, a terrestrial chamber on the top with soil, plants and invertebrates, a filter chamber with sand and gravel, and an aquatic chamber with fish and water plants. For supplies needed, read the previous post.
Cutting the bottles
This is a “how-to” video explaining how to cut the bottles and create drainage holes in the lids.
Students thoroughly enjoy building ecocolumns. The supplies here are for an ecocolumn with three chambers: A terrestrial chamber on the top with soil, plants and invertebrates, a filter chamber with sand and gravel, and an aquatic chamber with fish and water plants.
I begin Ecocolumns the 3rd week of school in the fall. To prepare, I ask students to bring in 1 gallon “Crystal Geyser” water bottles. They can be empty or full. I like the water bottles, because they are sturdier than 2-liter soda bottles, don’t tip over as easily, and many families don’t drink soda anymore. (But, many teachers still use soda bottles just fine) Students can donate the purified water in buckets which can be used later on in lab. You can also ask teachers to donate bottles as many teachers at my school bring water for their own use in their classrooms.
Students need 3 bottles to build, but I always have them bring 4, because many need a spare for a mistake cutting the bottles.
I’m not very strong and can hurt my back easily, so I drag my teenage sons with me to buy supplies. Since I teach 5 sections of APES with 9 groups of students per class, that’s 45 ecocolumns to buy for.