TITLE: Name That Line

SUBJECT: Algebra

TOPIC: Linear Equations

INTERACTIVITY: Students will randomly select numbers to define ordered pairs for two points on a line. Red numbers range from -5 to 5 and blue numbers range from -3 to 3. (The purpose for the difference in ranges is merely to ensure that the y-intercept of the line constructed is on the graph.) The x and y axes range from -15 to 15. Students will position a magnetic thumb tack at each of the points. They will then attach the line to the two points. Students will then count blocks to determine the slope of the line and will observe the y-intercept.

DIRECTIONS FOR USE:

- Randomly select two numbers from each of the “Random Number” boxes.
- Attach the red numbers you selected to define the ordered pair for Point A.

Attach the blue numbers you selected to define the ordered pair for Point B.

Record these points on your worksheet.

- Place the magnetic “Point Tacks” at these coordinates on the graph.
- Attach the line to connect the two points.

- Determine the slope of the line using:
- Remember: For Rise - Up is positive
- Down is negative
- For Run - Right is positive
- Left is negative
- Be sure to begin at the same point for both rise and run.
- Record the slope on your worksheet.

- Observe the y-intercept of the line.
- Record the observed y-intercept on your worksheet.

- Return the line, magnetic point tacks, and numbers to their original places.
- Repeat this procedure creating 6 lines.

TIME: I estimate this activity would take students 5-10 minutes at the bulletin board, followed by another 15-20 minutes to complete the worksheet. (It took me about 5 minutes at the bulletin board, then another 5 minutes to complete the worksheet.)

SPECIAL CONSTRUCTION: The grid is contact paper which had the red lines space about 3/4 inch apart. I traced over every other line in black to identify the tick marks on the graph. Magnetic thumb tacks were constructed by hot gluing thumb tacks to round magnets. The line is part of a metal wreath stand.

CREDIT: Students will receive a homework pass for completing this activity. The intent behind this is to offer the students the opportunity to choose to complete this activity instead of the homework assignment on defining linear equations. (This would be explained to the students when introducing the bulletin board to them.) Since this provides extra practice in naming lines and encompasses material covered in several lessons, students will be allowed to complete this activity twice, earning a maximum of two homework passes.

OTHER COMMENTS: I am concerned about the strength of the magnetic hold on the line. I will only be able to see if this holds up once the bulletin board is in place. (I may need to resort to painting a wooden dowel with magnetic paint, available in craft stores but a little expensive.) I also considered reminding students that the stick being used for the line is not a toy or a weapon (such as a sword). I would make sure to mention this when introducing the activity to the class, but depending on the maturity of the students I may need to place a warning note on the bulletin board as a constant reminder. And if the bulletin board was placed in a more public location than my classroom, I would include a note on the bulletin board reminding (warning) students not to play with the line or I would keep the line in my classroom allowing it to only be available upon request.