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Activity

## Graphing Linear Equations

Use Finch to model linear equations using slope-intercept form.

#### Free Teacher Materials

## BEGINNER: Outputs Only

**Required lessons: Moving & Turning**

Students will graph linear equations by programming the Finch to start at the y-intercept and repeatedly move according to the slope (rise over run).

*Steps:*

- Mark the origin and axes of your centimeter coordinate grid.
- Give students a linear equation and have them identify the slope and y-intercept.
- Put a marker in Finch’s marker hole and place the tip of the marker on the y-intercept. Make sure Finch’s beak is aligned with the y-axis in order to create an accurate graph.
- Program Finch to move forward “rise” and right “run” centimeters at 10% speed. Repeat 3 to 5 times. To increase accuracy, place wait/pause blocks after each move and turn.
- Note: moving forward negative centimeters will make Finch move backward. Try this on your equations with negative slopes!

- Once Finch has drawn the steps, remove Finch from the graph and draw your line using a yardstick.

**Tip**: Reduce Finch’s speed to 10% or less to increase accuracy.

## ADVANCED: Going Further

**Required lessons: Variables**

The same lesson above can be completed using variables! Create variables for rise and run to use in the loop and move forward blocks.

## MATERIALS

- Butcher paper or poster board
- Ruler with cm OR use our new Finch Math Mat for your coordinate plane!

## STANDARDS ALIGNMENT

**Understand the connections between proportional relationships, lines, and linear equations.
**CCSS.MATH.CONTENT.8.EE.B.6

Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.

**Analyze and solve linear equations and pairs of simultaneous linear equations.**

CCSS.MATH.CONTENT.8.EE.C.7

Solve linear equations in one variable.

**Define, evaluate, and compare functions.**

CCSS.MATH.CONTENT.8.F.A.3

3. Interpret the equation y = mx + b as defining a linear function, whose graph is a straight line; give examples of functions that are not linear. For example, the function A = s2 giving the area of a square as a function of its side length is not linear because its graph contains the points (1,1), (2,4) and (3,9), which are not on a straight line.

**Use functions to model relationships between quantities.**

CCSS.MATH.CONTENT.8.F.B.4

Construct a function to model a linear relationship between two quantities. Determine the rate of change and initial value of the function from a description of a relationship or from two (x, y) values, including reading these from a table or from a graph. Interpret the rate of change and initial value of a linear function in terms of the situation it models, and in terms of its graph or a table of values.