Big Idea

A few years ago, I wanted to find an easy way for students to practice writing conclusions and supporting them with evidence and reasoning – also known as CER – without having to do a complicated lab or a case study. At the time, I was planning to have students learn about lab equipment, when I thought about combining the two: learn about lab equipment and practice CER.

So, I had students take out and look at some lab equipment and answer the following question:

“What is this piece of lab equipment used for? Explain using the CER – or claim, evidence, reasoning- format.”

To answer this question, students need to observe an object’s form and relate it to its function.

For example, consider the graduated cylinder. What is it used for? It’s got these very detailed markings on the side. It’s got a groove at the top and a wide base at the bottom.

Now, let’s answer the question through a CER statement.

• Claim: A graduated cylinder is used for measuring out and pouring liquids.
• Evidence: Graduated cylinders have a grooved spout, detailed markings on the side, and a wide base.
• Reasoning: the detailed markings and wide base make it easy to pour in and measure liquids accurately while the grooved spout makes it easy to pour out or transfer those liquids into other containers.

Resources

Handout(s): Handout – 1 Way to Teach Lab Equipment & Practice CER

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Big Idea

In today’s back pocket science lesson, I try to determine which parts of the body are more sensitive than others. It’s what I’m calling the Simple Nerve test, and you’ll need a ruler, a paper clip and a pencil and paper to record the data.

First, take a paper clip and unwind it into a ‘U’. Use a ruler to help you adjust the width between the tips of the ‘U’ so that they are 2 cm apart.

Next, find a part of your body to test – like the forearm – and have a partner help you test. Have your partner poke your forearm with the paper clip with either one or two tips while you guess how many tips – 1 or 2 – you were poked with.  And, make sure you record whether the guess was right or not too. Do 10 pokes, and then switch roles.

Then, adjust the width of the “U” to 1cm and repeat.

Then, repeat the lab but with a different part of the body.

Compare which parts of the body had more accurate guesses. The areas where the guess percentages are higher are more sensitive than others.

Resources

Handout(s): Handout – Simple Nerve Test

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Big Idea

For this Back Pocket Science Lesson, I show my students a can of duster, I tell them that I wonder if it’s all a scam, and I ask: what test could I perform to determine if the gas in this can is different than, let’s say, the breath coming out of my lungs.

Some say “taste it!” or “inhale it” to which I respond, “we don’t taste or inhale any substances purposefully in science class” followed up by, “I know what you’re looking for – you’re looking for different properties compared to regular air – but is there any property I can test that doesn’t require tasting or breathing?”

One simple test is to measure the density of the air from my lungs and compare it to the density of the gas from a can of electronics duster. Density is basically the amount of stuff or mass that is packed into a volume of space. Every material has its own density.

First, fill up the one balloon with duster. Then, blow up the 2nd balloon to approximately the same size. Here’s a pro tip: it’s better to blow up the balloon after filling the first balloon with duster because it’s easier to adjust the volume. We want the balloons to have the same volume because then we can more easily compare any differences in density. If there is no density difference, then both balloons will feel and behave the same way and, therefore, we can reasonably conclude that both balloons would contain the same gas if this was the case.

There’s a few things you can do to compare balloon densities. The simplest way is to hold one in each hand and you’ll definitely feel a difference in mass. One balloon definitely has more mass, and therefore, is more dense. For a more precise observation, you could weigh the balloons separately. Finally, you can drop them side by side and compare their fall. Balloons with different densities will hit the ground at different times.

As you will see from the video, the balloons will hit the ground at different times. Therefore, the balloons have different densities and, therefore, different gases. So, I guess duster isn’t just regular air that’s been bottled after all.

Resources

Handout(s): Handout – Electronics Duster Dilemma

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