# Labs from YSI 94 : Simple Measurements.

April Whitt
CARA Yerkes Summer Institute, August 1994

This is a Teacher's Guide.

## Objectives

Students will determine the height of objects using shadows

## Materials Needed

meter sticks, protractors, Metric & English plastic rulers

## Procedures

Problem:
Students will determine a method for calculating the height of a nearby tree or the observatory. They may not measure it directly. Teams of students are taken outside and shown the objects to be measured. Teams may brainstorm their own solutions. The only equipment available to them is meter sticks and protractors.

Possible Solution:
Height of the building. Stand a meter stick or yard stick in a vertical position and mark the end of its shadow. At the same time mark the end of the shadow of the building. Measure the length of each of the shadows. (Each student will mark and each student will make measurements. If there are three students in a team, then the team may have three different measurements.) The height of the building can then be found by using a proportion equation:

```height of meter stick         length of shadow of meter stick
---------------------    =    --------------------------------
height of building           length of shadow of building
```

Example:
Length of shdow of meter stick = 2 meters.
Length of shadow of building = 20 meters.

``` 1 m      2 m
-----  = -----   --> H = 10 meters.
H      20 m
```
Important Disclaimers and Caveats: