There are many things that I’m not really great at. Cooking. Organizing. Crafts. None
of these really seem to be for me. And you know, I try to keep a growth mindset so I
know that if I truly was interested and wanted to grow my skill, I could. I mean, over time
with our videos, you can see our art and our audio has gotten…better. It’s taken a
lot of years and practice. But to be honest, those three things have never really piqued
my interest so I haven’t really developed a skill for them. Yet.
But one thing I am good at, or at least I think I’ve developed, is being curious about
things. You know, many people start out being very curious from a young age. But for some
reason, as we get older, sometimes, we sort of stop asking as many questions. I think
I just stopped asking them out loud.
I used to have a pond near my house where I grew up in Texas. There would be these semi-aquatic
turtles that would sun themselves on this floating log in the pond. Most of them were
red-eared sliders.
But every winter, they were gone. I don’t know where they went. Did they migrate like
birds? Did they hibernate, and if so, where? I mean these turtles spend their time in the
water, and you usually only see them outside of the water if A) they’re sunning themselves
or B) they’re laying eggs. Since we live in Texas, the pond didn’t completely freeze,
but there was at least an inch of solid ice at the top. I know that red-eared sliders
breathe oxygen by coming to the surface as I’ve seen them do that, and they don’t
have gills. If the pond surface freezes over solid, they would not be able to do that.
So, yes, this is going to leave me with questions, and questions are a a great start to being
curious and can lead to some fascinating scientific investigations. In our Nature of Science video,
we talk about how the science process is often not linear, how there’s not just one universal
scientific method, and we list some important things to consider when planning a scientific
investigation. But after a scientific investigation, how might we develop a scientific explanation?
Right now, we want to talk about a framework that is applicable to a lot of subjects – not
just science – and therefore not just biology that I teach. It’s actually cross-curricular.
And that is CER. Claim Evidence Reasoning. However, not necessarily conducted in that
order. CER is a framework that can be used for scientific explanations. Due to this,
it’s very popular in science classrooms. One way to use this CER framework is to help
develop a reliable conclusion after an investigation has already been conducted. A conclusion can
state the claim, evidence that supports it, and reasoning for how or why that evidence
supports the claim. As an example, let me go back to that turtle situation.
So my question: In the winter when the pond surface freezes over, where do all the red-eared
sliders from this pond go to survive? I could launch a full investigation on this, and part
of my investigation is where I would obtain data. I’m not going to show all the steps
of a potential investigation right now: if I did, I might show the steps in developing
my hypothesis and my procedure. But for this short video, we’re going to focus on the
data collected in an investigation, because that data will serve as my evidence and I
cannot have a claim without evidence that supports the claim. I want to use the Claim
Evidence Reasoning framework to help me write a portion of my conclusion – and remember,
that’s only one example of how I could use this CER framework.
So in my investigation, my data includes many observations - whether the turtles are leaving
the pond or staying in the water. I might set up cameras for footage of the pond or
in the pond, observing exactly what they are doing in the water, although I’d need to
be careful not to disturb the turtles in any way. I’d be observing before the winter
and after the winter is over. My observations show that these turtles are remaining in the
water when the pond freezes over. Also, the same turtles are present after the winter
is over. I also observe the turtles’ inactivity in the water at the bottom of the pond when
the pond’s surface freezes over.
My investigation would also include research: information from science papers from science
journals about red-eared sliders. With this research, it’s important to examine where
my source comes from. This is likely beyond what we’d find in a general biology textbook,
because this is a very specific topic about how red-eared sliders handle the winter. Are
the sources I’ve gathered actually peer-reviewed science sources from a science journal? Maybe
it’s written by an expert in the field? Or…is it info from a website your neighbor
Bob made who had a turtle once and has many personal opinions about turtles – which
is not how science theories work by the way – and likes to take pictures of turtles
in his spare time and post them online with random filters? Always, always consider your
source- I am looking for factual, peer-reviewed sources.
Keeping that in mind, I gather science papers that talk about freshwater turtle winter survival,
and I notice these papers discuss brumation. Brumation has similarities to hibernation
- you might be familiar about hibernation in mammals. Brumation can be done by ectotherms
like red-eared sliders. During brumation, red-eared sliders can handle a low oxygen
environment and the turtle's metabolic needs slow down along with other physiological changes.
If I had appropriate equipment and sufficient training, I might obtain quantitative data
demonstrating the physiological changes occurring.
So, if considering the CER framework, I may perhaps use this to help me organize a portion
of my conclusion at the end of my investigation. My claim (which answers the original question)
: In the winter when the pond surface freezes over, red-eared sliders from this pond remain
in the water and brumate. My evidence, which supports my claim: I would provide the qualitative
data consisting of observations of the turtles’ activity and, also, I’d like to include
the research I’ve cited from peer-reviewed sources about red-eared slider brumation.
But I can’t just report my evidence and say, “Here’s my evidence!” and be finished.
I’m going to do my reasoning now which shows how or why my evidence supports my claim.
The evidence supports my claim, because the evidence shows that the turtles stayed in
the water over the winter and that those same turtles survived the entire winter in the
water – they were still alive and in the water after the winter was over. In addition,
the peer-reviewed sources I’ve cited define the general inactivity of the turtles that
I had observed as brumation and how red-eared slider turtles can brumate in the water, and
the physiological changes that happen during brumation even when the surface freezes over
in the winter.
One last thing. As we mentioned earlier, CER is useful for more than your biology course.
You can apply CER to your daily life. Next time you hear a claim from someone or read
a claim online, consider that CER framework. Is there evidence to support the claim? And…can
you provide the reasoning for how or why the evidence supports the claim? Well, that’s
it for the Amoeba Sisters, and we remind you to stay curious!