The illusive photosynthesis experiment. This student has a good start but has a lot to figure out.
“I want to do something with plants”
My heart sinks.
“How about the effect of acid on plant growth?”
Cringe.
“How does light intensity affect photosynthesis?”
Heavy Sigh.
What do these ideas for internal assessment ideas mean to me? Often, failed experiments.
For whatever reason, students think setting up a plant experiment will be easy. They never factor in the time it takes to determine the best conditions to grow their plant or sprout the seeds. It often results in a neglected, unwatered project of withered specimens.
It's always a temptation to check: maybe this one will work.
And I know this. So why don’t I just say, “no plants”? That approach would be notably simpler and it would spare me the pain of watching those pathetic seedlings atrophy and die at the back of my classroom. However, it is my firm belief that students, especially 16-18 year old IB students should have their own choice. The choice fosters ownership in their work. And if they really want to do it, then they deserve a chance to try, right? So, after bequeathing warnings about how difficult plant experiments really are and that statistically there have been few true successes come from them, I allow my students to proceed. For some reason, they always think their situation will be different.
Though I noticed the deteriorated state days ago, a student came to me today and showed me his shrivelled seedlings as though they’d “just perished”. He was running a pretrial to determine whether he would best conduct his experiment in cotton or soil and approached me with the observation, “ I think soil worked better than the cotton”. He looked down at me with his big brown childish eyes hoping for confirmation and I’m thinking, “Seriously? They’re ALL DEAD!” but I just smile and ask him how many of the 5 seeds in each cup actually sprouted to which he responds, “One”. “So what does that tell you?” Silence. Thinking. Wheels turning. “That I need to plant ten in each cup?”
Exasperation is threatening to settle in but I patiently continue, “Well, that might be a choice you make, however, what is the actual observation?” More silence. Thinking. Wheels turning. “Um, that not all the seeds sprouted?” He receives the advice to consider these observations as he proceeds. Of course I know he’s baffled in attempting to incorporate this information into subsequent planning. He returns the blighted seedlings to the fluorescent lamps though I’m not sure why. They should be tossed in the rubbish bin.
Then there's the photosynthesis experiment that's been sitting in my lab area for five days. It's obvious to me that the set-up isn't optimized, however, the student keeps returning hoping to see a measurable amount of oxygen. At what point will she realize that no more oxygen will appear in the tube? Tomorrow I will tell her it's time to reconsider her design.
So, in the end, the students who were counting on an easy experiment with their plant idea often give up after the first attempted failure. Others persist repeating over and over again until they get it to work. They always spend so much more time than the students who design an experiment in which data can be collected within a day.
Regardless of the design choice, it’s the most difficult thing to resist telling them what to do. The path of “no choice” is decidedly more manageable! But that would deny my students the purpose of this journey.
Students work their way through the scientific process. They deal with frustration, glitches, and failed attempts but in the end, they all end up with two reasonably controlled experiments that they have designed and carried out. And they are always proud of their work.
To all of us out there struggling to let go of the control, just do it! The students will be rewarded with a worthwhile journey that leaves them feeling accomplished and you will be profoundly happy for them.