Climate Change in Terrariums

Isobel Harper

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Grade 5/6s at St Pius X  created their own mini biospheres

When we start projects in class I usually know how they will end, but sometimes a wild idea takes things in a whole different direction. This was the case with a project we did with the 5/6s last year.

In Foodweb sessions we have two sayings we use all the time: "Energy flows from source to sink but matter cycles round and round" and "Things can move and things can change but things don't go away" 

These sayings help us to remember that all the stuff, the matter, here on earth is here to stay but the energy that moves it all around is constantly flowing in and then out of earths systems (as latent heat). To put it another way; The earth as a system is energetically open and materially closed.

In Foodweb sessions we are always looking for interesting ways to explore this concept of earth as a materially closed system and last year we set the kids the task of designing their own closed systems. We made our own mini-biospheres or mini-ecosystems otherwise known as terrariums. We talked about what we would put in there; how much soil? how much water? what plants might survive or die? would it be ok to put bugs in there? where should we put it in relation to the sunlight? We wondered how things might change inside.

We observed our terrariums weekly and many interesting things happened, plants grew that we didn't remember planting, moulds flourished, and chewed leaves provided evidence of bug life.  We were pretty happy with how they turned out, life continued in the mini-biospheres.

It was when we got talking about the first great extinction on earth that the wild idea may have been concieved. We read a story about how Cyanobacteria caused the first mass extinction on earth, filling the atmosphere with oxygen which was toxic to most of life on earth at that  time and changing the climate. on the last day of term we were trying to decide what to do with our terrarium experiment, pour the contents in to the garden? take them home? The kids decided they wanted to experiment with the climates of their terrariums. I was swept away by their enthusiasm so we put one of them in the freezer for the afternoon and the other in boiling water.

It wasn't until afterwards that I realised the potentially heavy implications that boiling our home made bio-sphere may bring about in light of our current situation with climate change on the planet (not to mention the worm sacrifice!).  To be honest I think the kids were so caught up in the excitement of seeing what happened that we didn't discuss them as a metaphor for our own planet. I'm still not sure if this was a missed teaching opportunity, an ethical overstep or an implied lesson. It's always a risk following a wild idea and sometimes its not clear if it was successful or not but it sure keeps teaching interesting.

Isobel Harper