[PASCO Wireless Sensors]
[Diffusion]
Mike: Hi, I'm Mike Blasberg, the Biology Education Manager at PASCO.
Barbara: I'm Barbara Pugliese, Curriculum and Training Specialist at PASCO.
Today we're going to look at a PASCO SPARKlab called Diffusion,
where we look at a model of a cell membrane
with dialysis tubing and investigate passive transport in that membrane.
I'm going to open the Diffusion lab.
The first page that comes up is materials and safety,
followed by some background information about the lab
and also the main idea of the lab,
some questions to prime students' memory,
and then the instructions.
M: We'll begin by connecting the Wireless pH Sensor.
We'll press the power button to turn the sensor on.
Notice that the Bluetooth's LED blinks red,
indicating that it's ready to pair.
B: Now that it's ready to pair,
I'm going to click the Bluetooth menu icon.
I see the pH sensor, so I'm going to select it.
And I'm done. It's connected.
M: The first measurement we're going to take
is of some vinegar and blue food coloring,
which is acting as our intracellular fluid.
We'll place the sensor in the solution,
and then wait for the reading to stabilize.
That looks great.
B: It's at 2.6.
So I'm going to record that in the text box: 2.6.
M: I'm going to rinse the sensor before we begin our next run.
B: It's a good idea to remind students to scoot the lid up
on that pH sensor so it does not get into the solution.
M: We're going to place the sensor in the (distilled water) solution.
We've already prepared our model cell with dialysis tubing,
and it's filled with the vinegar and blue food coloring solution.
We'll now place that into the beaker,
and clip it to the side so it stays in place.
B: I'm going to start data collection.
Data collection will run for about five minutes,
so we'll come back in five minutes
and look at the last minute or so of data collection.
B: We're coming up on five minutes here,
so let's stop data collection.
It looks like it's starting to level off.
It looks like nothing happened,
but if we go to the tools and scale it,
we can see more of a change.
I'm going to select the first minute of data,
and I'm going to select high above and to the left of the first data point
so that I make sure that I include it.
There's my first minute.
I'm going to click Done.
I'm going to use the curve fit tool to select a linear fit
in order to get a slope equation
to get the rate of change of pH over time.
You can see the first initial rate is dropping by 0.0249.
I'm going to enter that in the text box
and I'm going to compare that to the last minute of data.
Using the Select tool, I'm going to click Done,
Curve Fit, and Linear Fit.
The slope equation comes up, and I get -0.0168.
M: The pH data is what we would expect,
given that as diffusion continues,
the concentration gradient is going to decrease,
so the rate of diffusion will also decrease.
At this point, students can go on and complete the lab
to measure the pH of the solution inside of our model cell,
to see if it changed from the original data point,
and then also complete an optional inquiry extension.
B: If you would like more information on this wireless sensor,
or any other sensors, visit pasco.com/wireless for more resources.
Thanks for watching.
M: See you next time.