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

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

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.

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