View Tube Triangulation

Pete Insley                    Jones Metropolitan H. S.
                               606 S. State St.
                               Chicago IL 60605   
                               (312)534-8600

Objectives:

     Measuring Distance; Estimating; Averaging; Standard deviation

Materials Needed:

     Meter sticks, rulers, cut down paper towel cardboard tubes

Strategy:

     First, get the students to estimate the height of the chalkboard or the 
doorway.  List the estimates and use a calculator to find the average and 
standard deviation.

     Stand far enough away so that you can see the entire object in the tube.  
Use a proportion to find the height of the object.

                   Height of object   =   Distance of tube
                  Distance to object       Length of tube

     List the calculations and again find the average and the standard 
deviation.  Take some time to discuss what they mean again. 

     Now get a couple of students to measure exactly how big the object is.  
Have a prize for the best estimate of measurement.

Performance Assessment:

     Collect paper with original estimate and calculation of height.  Have 
students write a short paragraph stating how well they think they did on the 
exercise.

Conclusions:

     You can find percentage error in this lab and it has some new meanings to 
the students.  Have them find their % of error.  You can also find the probable 
percentage of error from the standard deviation.