Teaching Algebra with Manipulatives

Demonstration 2
Writing an Equation of a Line
• Display this graph on a second coordinate grid transparency.
• Ask students to name the coordinates of M and N. (0, 0), (1, 4)
• Ask students how to find the slope of the line from the
coordinates of these two points. by dividing the change in y
by the change in x
• Write the formula for the point-slope form of a linear equation
on the blank transparency.
y y 1
m(x x 1
)
Using Overhead Manipulatives
y
N
O M
x
Algebra 1—Chapter 5
Substitute the slope and the coordinates of M in the equation.
Have students tell how to simplify the equation and write it in
standard form. 4x y 0
• Have students substitute the coordinates of N in the slope-intercept
form. Ask whether the same equation results from using the coordinates
of M, N, or any point on the line. yes
• Ask students to name a different point on the line. Answers will vary.
Have students show that the point is on the line.
© Glencoe/McGraw-Hill 101 Teaching Algebra with Manipulatives