# Teaching Error in Measurement Lab

1. Aug 12, 2014

### CSOleson

Hello all, as a recent graduate and a new teacher, I am living in Honduras and teaching the sciences in a high school setting. I did not study to be a teaching by got my bachelors in Spanish and Physics. I am working at a bilingual school and my resources are extremely limited.
My question is regarding teaching some of my labs. The first on error in measurement and teaching them how to find percent errors, etc. What is a good, minimalist way to teach this? Any ideas would be greatly appreciated!

2. Aug 12, 2014

### Rocky9242

There are many ways this could be done.

Have them measure the thickness of the textbook and calculate from that the thickness of a single page. Averaging 20 or 30 of these measurements will give you a very accurate estimate. Measure the "real" thickness with a micrometer.

Give each student something round--coin, jar lid, etc.--and have them measure the diameter and the circumference with a ruler, or by wraping a string around it, or by rolling it along the table top. Perhaps have each student or pair of students use each of these three methods. Calculate the value of pi from the student data. You'll be surprised how many sig. digits you get by averaging a bunch of these together. Calculate mean and standard deviation by groups, such as by measurement method, or by groups of students.

Lay sheets of paper on the ground in front of all four tires of a car. Pull the car forward so each tire is in the center of a sheet. Use a pencil to trace the footprint of each tire onto it's sheet of paper. Do this carefully so the area of the tracing very closely matches the area footprint. Measure the area of each footprint and add them together. Measure the air pressure in the tires. The weight of the car is the total area of footprint multiplied by the average tire pressure. (or simplify it by making each tire have the same pressure before you begin). e.g. Weight = cm^2 x (kg / cm^2) or weight = in^2 x (lb / in^2) (I'm not sure what the proper metric units would be here, maybe Pascal?)

Make a rummy balance by balancing a meter stick in the middle on a knife edge. Place a coin of known weight at the 10 cm mark and move the fulcrum to balance the meter stick. Put a drop or a few drops of water at the 99 cm mark. Slide the coin toward the end to rebalance the meter stick. Do some arithmetic to calculate the weight of the water drop(s).

Last edited: Aug 12, 2014
3. Aug 12, 2014

### Rocky9242

The way to find things like this on the Internet is to search for:

physics demonstration experiments

or

physics classroom demonstrations

and maybe add the level of the students, e.g.

high school.

Last edited: Aug 12, 2014