# Activities

• • • ##### Subject Area

• Math: Algebra I: Linear Functions

• ##### Author 9-12

40 Minutes

• ##### Device
• TI-83 Plus Family
• TI-84 Plus
• TI-84 Plus Silver Edition
• TI-Navigator™
• ##### Other Materials
Per group:
Water container with mL measurement (can fit at least 500 mL).
30mL of water per group.
10 big marbles (same size)per group
1 graphing calculator connected to TI Navigator.
• ##### Report an Issue

Fill up the tank!

#### Activity Overview

Demonstrate the concept of slope and y-intercept in the slope-intercept form of linear equation using water and marbles.

#### Before the Activity

Divide the class into groups of 4 members.
Define the variable that we will be using in the activity.
Let x = number of marbles
Let y = water level

#### During the Activity

Students record the water level every time they put in 1 marble using the attached form - fill up the tank.doc.
After the students have put it all 10 marbles, start the Activity Center and ask the students send in their data using the activity setting fill up the tank.act.
Then have a little discussion what the points represent especially the one on the y-axis.
Ask the each group to model the situation with a linear equation in the form y = mx + b.

#### After the Activity

Have a discussion on:
Why the y-intercept is 30
The significance of the slope
What the slope represents