Lesson 2:

Concepts conveyed | Materials | Procedure | Benefits

Concepts conveyed:

The purpose of this demonstration is to illustrate, in a practical fashion, measurement and how it relates to the field of chemistry. Precision, accuracy, and unit conversions are involved.

Materials:

(for one group of students)

• 1 measuring device (with increments of inches, meters, feet, and/or centimeters). Each group of students should have different shapes and sizes of measuring devices.
• 1 object on school grounds or in the building for the students to measure (each group will choose something different to measure)

Procedure:

Ask students to get in groups of three to five and assign each group an object that can be measured or ask the group to choose their own object. Give each group a measuring device and ask them to measure the object in feet, inches, centimeters, and millimeters. The measurements that cannot be directly obtained, due to limitations on the measuring devices, can be calculated or derived from the ones that can be directly obtained.

Require students to perform the activity in a limited amount of time (e.g. fifteen minutes). Select some students to initiate discussion about their results. Ask for results to be written down and handed in at the end of the class period.
Example: Ask a group of students to measure the front door of the chemistry building with a six inch ruler.

Benefits:

• In the future, the measured object can serve as a visible reminder of the lessons taught here.
• The instructor can use the data obtained from students as a part of the lecture. This includes the advantages and disadvantages of measuring objects larger and much smaller than the device, conversions between units, concepts of precision and accuracy.
• The results that are received from the students can be used as a means to check classroom attendance and possible to award extra credit points.