Education Technology

# Activities

• ##### Subject Area

• Math: Algebra I: Exponential Functions

6-8

60 Minutes

• ##### Device
• TI-73 Explorer™
• ##### Other Materials
This is Activity 7 from the EXPLORATIONS Book:
Activities for Algebra with the TI-73.

The following materials are required for this activity:
• Metric ruler (meter stick)
• String of length: 1.5 meters
• Eye test sheets with letters

## Now You See It, Now You Don't

#### Activity Overview

In this activity, students' study the relationship between age and near point accommodation (NPA). They predict a person's age using NPA distance values. They use exponential regression, create box-and-whisker plots and histograms.

#### Before the Activity

• Set up the calculator for data collection using the procedure described in the attached Appendix PDF file
• See the attached PDF file for detailed instructions for this activity
• Print pages 87 - 96 from the attached PDF file for your class
• #### During the Activity

Distribute the pages to the class.

• Measure the closest distance between the eye and the paper when the letter on the paper remains in focus (NPA)
• Record the age, and the distance between the eye and the paper
• Repeat the procedure with 4 different subjects
• Enter the age and NPA data for subjects in three different age groups as lists
• Group the data for different age groups
• Create a box-and-whisker plot to analyze the data
• Find the median near point accommodation of the three age groups analyzed
• Observe that higher the age the greater the width of the box plot
• Use the graph of the exponential regression to determine the person's age based on his NPA distance
• #### After the Activity

Students' will complete the Data Collection and Analysis page and answer questions.

Review student results:

• As a class, discuss questions that appeared to be more challenging
• Re-teach concepts as necessary