In this lesson the students will observe a pattern of tiles. 

Project the patterns on an overhead projector.  Students should record the picture number and the number of tiles in the corresponding picture on their chart.

Have students look for a pattern in the table (number of tiles is always larger than the picture number, number of tiles is increasing, number of tiles is increasing by 4.)

Have students predict the number of tiles in the next picture.  Where will the extra tiles be placed? 

Have students rewrite the Number of Tiles to reflect the change taking place.  (5+4, 5+4 +4, etc.)

 Using this technique have students describe the number of tiles for several other picture numbers up to Picture 10.

Have students observe what they have written and write an expression for the number of tiles in the nth picture.

Have students turn on their calculator and follow the steps for entering data in the TI-73

After students have their data in their calculator they set up the calculator for a scatter plot.

The students should next set an appropriate window to reflect a scatter plot for their data.   

When the data has been entered, a plot has been turned on, and an appropriate window has been set the students can press GRAPH.

What does the graph illustrate?  (Points for a straight line, points keep getting higher as you move to the right, etc. )  Students can trace on the picture by pressing TRACE and using the cursor arrows.  What are numbers are the bottom of the screen illustrate?  Ask students to observe how the x values are changing.  How are the y values changing?  Is the graph illustrating anything that the pictures illustrated? 

Ask students to press Y= and enter their expression for the number of tiles in the nth picture in Y1 by replacing the n with an x.    Press GRAPH and describe what happened.

To view a table of this equation set up a table.  What does this table illustrate about the pictures?  How can you use this table?