# Creating a Unit of Measure to Teach Measurement

Posted on: June 6, 2011

There has been a lot of talk on the NSTA Physics list server lately regarding a way to teach a measurement lab.  I had one of my morning shower brainstorms.  My thoughts went to the story of the MIT students measuring a bridge using a unit of measurement called the “Smoot,” named for Oliver Smoot.

I think many of us teaching a measurement lab have the same problem.  The students don’t understand measuring or estimating.  Given an object, they will always have the same answer, regardless of whether it is right or wrong.  So I am hereby creating a lab using fictitious units.  We will use a willing volunteer from each lab group and declare his or her height to be one “Smith” or “Jones” or whatever his or her name happens to be.  We will then do some exercises to estimate fractional distances.  I think I will give them string and make them use a meter stick to get a measurement of the “Smith.”  They will need to figure out how to divide the string into tenths and hundredths and then estimate to the thousandths.  I won’t tell them how to do it, they are going to need to figure it out on their own.

My hope is that they will come up with their own method and get a better understanding of estimation.  The beauty of an inquiry lab is how little detail they get from me.  Personally, I’m excited about this one.  I think we are looking at a first or second day of school lab here.

Here is my first pass at the lab handout.  Lab 00 – Measurement Lab

You can read about Oliver Smoot and hear an NPR interview here.

### 16 Responses to "Creating a Unit of Measure to Teach Measurement"

What instantly comes to mind is, after establishing their unit (and creating measurement instruments of some sort) to have them do some measurements, and report say the length of the hallway in “smiths”, “joneses”, and “wus”. Then report the area of a table top in square centismiths. Then the volume of the room (or a glass of water) in cubic millijoneses.

Now create conversion factors between smiths, joneses, and wus.

Now analyze video of a vehicle travelling along the road next to the school. Report velocity in joneses-per-second.

Discuss the measurements together. Let the difficulty in converting create an environment where they want to standardize to a single unit of measure.

Now you can discuss the reasons for the development of systems of measurement and the commonly used metric system.

Jim,
I really like most of your ideas. The only part I’m pushing back on is the velocity measurements because we don’t discuss that until chapter two and I don’t want to get ahead of myself. Measurements, conversions, significant figures, and scientific notation are all part of chapter one. I have a 90 gallon fish tank, I wonder what that is in cubic millivaders?

I really like the idea of discussing a standard and leading to the standard system we use in the course. Nice connection.

Sounds like a great idea!

I am going to try this tomorrow for my 1st day of Physics. My kids vary wildly on math skills, so I am interested to see the methods they come up with. Thanks for sharing!
Rebecca

Rebecca,
I posted this as an idea that I haven’t tried yet, so please come back and fill us in on what you do and what works.

Where do you teach that school starts at the end of July?

Scott

Scott,
I teach in Southern Indiana. We are on a balanced schedule, so we get two weeks off after each 9 weeks in the fall, winter, and spring. Its not the norm for Indiana.

I am a 2nd year teacher, so I am still learning a lot. I also teach 5 classes (Biology, Biology II, Anatomy, Physics, and Integrated Chemistry Physics) so I am always looking for ideas.

Anyway, my physics kids did really well with this. I figured it would take them the whole period (about 50 minutes) and we might need to continue it the next day, but they all finished early so we were able to discuss it that day. I used the idea posted here from Jim to bring up SI units because scientists need a standard.

The only problem I noticed is when my students measured the “centivaders” (I called them potters because the kids here love Harry Potter). I wasn’t sure if they were confused or I was. It seemed to me because there are 100 cm in 1m they should have 100 centivaders, but when they divided up they had 10 centivaders. I think where they were measuring 1 centivader was 10 centivaders. I asked them about it when we were discussing and pointed it out on the meter stick, and they then seemed to agree with me. But I am not sure about that! I wanted to check with the math teacher because I think I’m confusing myself, haha.

Great engagement and discussions though. It was the perfect thing to do on the first day! They seemed excited to get to actually do something (especially measure in the hall between the classroom doors) instead of just listening to the rules and syllabus stuff. We did that on Friday, the 2nd day of school.
Rebecca

1 meter = 10 decimeters = 100 centimeters

I really like this idea too. This is my first year teaching physics (taught bio in the past), so I’m willing to try new ideas. I would like to incorporate this with the introductions to scientific notation, significant figures, and unit conversion. I teach block, so I was thinking one day review prefixes and have kids determine measurements using their decivaders or centivaders, etc., and maybe measure area and volume as a refresher. The next day, talk about how precise they can get, see what group can get the smallest prefix unit, and discuss sigfigs and precision. I would ultimately want to have them do unit conversion to meters, and see how close groups were to true metric values of objects and discuss the concept of accuracy.

I tend to get carried away and sometimes lose my audience, but I will let you know how it goes. I plan to try it the week of 8/23ish

Kasey, I’m curious if you developed a handout to go with your approach. Or Scott – when you did the activity, did you modify your handout? I’m a second year teacher planning to try this out next week with some kids who fall greatly into the category of being metrically challenged and would like to have a handout that worked well.

The handout I used is on the original post. I did this on the first or second day of school last year. It went over unbelievably well and I will definitely be doing it again on the first or second day every year. Last year, one group moved the student and marked the floor rather than use the string. They had a blast and figured all but how to subdivide into tenths.

This year I’m going to cut up a 2×4 to make some sticks that are about 6′ long. The kids can trim the stick to the length of the student. The only issue I had last year is that the string stretches. A stick won’t do that. I’m learning to give them as little instruction as possible and to let them work it out on their own.

I tried this today for the second day of class to get us started. I printed a copy of the Smoot story for them along with the activity handout. My class is predominantly senior boys, but they loved it! Some found it challenging to let go of their beloved meter stick and to just use their string they’d created. I’m excited to return tomorrow and watch them as they finish taking measurements and see if they connect the idea about our metric system and its divisions. Thanks for a great idea!

I love that this is working, but give me more details. Yes, I came up with the idea, but I haven’t tried it yet. I’ve been trying to work out how the kids will subdivide their unit of measurement without using another measuring device. Our carpentry tools continuously divide the units in half, so we get 1/4″, 1/8″, 1/16″, etc. How did they do tenths?

I would cut a second piece of string to the same length and then wrap that around my hand or arm and work it to get exactly 5 loops. Cutting it at the top and bottom will give tenths of a unit. They might be able to do the same thing but with smaller loops for hundredths, I’d have to try it to see. I suppose they could also cut paper and then mark it by eye, then cut it, lay them side-by-side and try to come up with the length that is the average.

This took my class of mostly seniors two days to complete. The part that troubled them the first day was how to divide it into tenths. Most had resorted to folding only to find that it gave halves. I reread the handout and saw that it did not tell them to put the meterstick up until after dividing into tenths. So I let them use it as a way to evenly divide. After struggling for a day, they had some lightbulbs going off on day two. They recognized that metrics are more than just memorizing where to put decimals with certain prefixes.

I’m curious to see what changes, if any, others made or problems they’ve encountered. I would love to use this again next year as it was a great way to start the first week of school!

I used my own idea the last two days. I allowed them to use the meter stick only to the point of measuring the length of the Stephy or Mindy. They all struggled at first to come up with the division, but soon figured out that cutting it first in half and then in fifths gave them tenths. For a few of them, I showed them mathematically that even if the pieces aren’t all the same size, if they eyed it and found about the average, it would be very close to exact. So most marked their string with the tenths and then estimated the next digit. None of them tried to subdivide the tenth into hundredths although they understood the idea.

What really worked, more than I expected was how this really got them thinking about the decimal units. Suddenly, they understood that they could measure 1.6 and estimate to 1.64 because they hadn’t subdivided any further.

One of my classes dragged Stephy head to heels and then used the calibrated string for the fractional Stephy. They had a blast and really got the concept. I had fun just watching them all work. It was a great way to start off the school year.

Nice ideas. I’m going to try it with my 8th graders this week as we start talking about measurement. I really like the idea of a stick or board rather than a string. It will be a cool thing to have on Parent Night too. I’m going to get some 1×2 or something of the sorts that I can cut easily with my jigsaw. I’ll let you know how it goes.

I will probably cut a 2×4 or 2×6 into 1/4″ strips on my table saw but I like the idea of 1×2’s, it certainly makes the lab easy for anybody to do.

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