High School Biology Chemistry Smile Meeting
12 September 2000
Notes prepared by Earl Zwicker

Glenda Ellis (Williams School)
marked a 30 meter course around the perimeter of the room, gave us stop watches, and we measured the time it took for each of us to walk the course. From this, the walking speeds for each of us were calculated and compared. Speeds ranged from 1.20 to 1.67 meters/second. Ken Schug recalculated the speeds in miles/hour! And we then had an interesting discussion about how our speeds compare with walking and running speeds of various animals: 

What a great way to get student's ego involved in an experiment, at the same time learning about the concept of speed and how it is calculated!

Erma Lee (Williams School)
turned us into bean counters! She gave us dried, red beans and asked us to estimate how many beans it takes to go around a person's shoe. Then we had to measure it! Erma asked us to trace an outline of our shoe on an 8.5 in  x 11 in paper, and then we did the measurement on the tracings, laying the beans end-to-end. The distance around was measured in "bean lengths." She asked us to measure the surface area within the tracing, a sort of surface area of a shoe. To do this we placed as many beans as possible within the outline and in a single layer, and counted them. We repeated these measurements for our hands using the same techniques. We found that the surface area of our hands was about 75% that for feet, and the perimeter of a hand (fingers closed) was about 80% that for feet. What a rich learning experience! - involving measurement, observation, comparison and conclusions. Thanks, Erma!

Karlene Joseph (Lane Tech HS)
had us write hidden messages on 8.5 in x 11 in paper by using phenolphthalein as an invisible ink. When we sprayed the paper with an ammonia solution (a base), the phenolphthalein turned red, and our messages appeared. Spraying with vinegar (acetic acid) caused the red to turn clear so the messages would disappear!

Now that she had us "hooked," Karlene did a titration of 15 ml of vinegar with ammonia using phenolphthalein as an indicator, and we found that about 12 ml of ammonia was needed to turn the vinegar to deep pink. Thus, the molarity of the ammonia was 15/12 = 1.25 times that of the vinegar. A wonderful phenomenological approach, Karlene!

Great ideas! Don't miss the next one!