Getting Started 
Misconception/Error The student is unable to correctly graph points in the coordinate plane. 
Examples of Student Work at this Level The student reverses the x and yaxis, reverses x and ycoordinates, or interchanges the positive and negative portions of the axes.

Questions Eliciting Thinking How do you know where to plot the point? What does the ordered pair (x, y) mean?
On a coordinate plane, which is the x and which is the yaxis? In an ordered pair, which is the x and which is the ycoordinate?
Where did you start counting from? Which direction did you move to plot the xvalue and which direction did you move to plot the yvalue? 
Instructional Implications Provide instruction on graphing points in the coordinate plane. Be sure to include points in all four quadrants and on both axes. Ask the student to both graph points given their coordinates and to give the coordinates of graphed points.
Provide the student with additional opportunities to graph specified figures given the coordinates of their vertices. 
Moving Forward 
Misconception/Error The student is unable to correctly find lengths of horizontal and/or vertical segments in the coordinate plane. 
Examples of Student Work at this Level The student correctly graphs the vertices but:
 Counts the number of unit squares that surround the rectangle and includes additional squares at the vertices.
 Counts grid lines instead of unit lengths resulting in a length of 11 and a width of six.

Questions Eliciting Thinking How did you determine the lengths of the sides of the rectangle? What is the unit of measure for length?
Did you count the grid lines, squares, or the lengths between the lines? 
Instructional Implications Review the concept of length and how it is measured. Directly address the misconception that length is calculated by counting grid lines or squares and give the student additional opportunities to find lengths by counting unit lengths on number lines. Guide the student to extend this approach to calculating horizontal and vertical lengths in the coordinate plane.
Review how rulers are used to measure lengths. Equate a unit of measure such as an inch to the spaces between notches on a number line. 
Almost There 
Misconception/Error The student makes an error in calculating a length or the perimeter. 
Examples of Student Work at this Level The student correctly graphs the vertices of the recangle but:
 Counts unit lengths to find the lengths of the sides of the rectangle and is off by one.
 Correctly finds the length of each side of the rectangle but makes a small error when finding the sum of the lengths.
 Finds the area of the rectangle rather than its perimeter.

Questions Eliciting Thinking What method did you use to get the perimeter? Is there a way to mark the paper as you count to ensure you count each unit length?
Can you add your lengths again to verify your answer?
What does perimeter mean? How is it different from area? 
Instructional Implications If needed, review the difference between the concepts of area and perimeter. Be sure the student understands the difference between linear units and units of area. Offer the student additional opportunities to calculate both area and perimeter of figures graphed on the coordinate plane. Have the student work with a partner to compare answers and reconcile any differences. 
Got It 
Misconception/Error The student provides complete and correct responses to all components of the task. 
Examples of Student Work at this Level The student graphs the vertices correctly, correctly finds the length and width of the rectangle, and calculates a perimeter of 30 units. The student gives a clear explanation or shows work clearly.

Questions Eliciting Thinking What would you do to find the area of the figure?
If the figure were moved to quadrants one and two, would the perimeter change? If it was rotated vertically, would that change the perimeter or area?
Can you change the location of two of the vertices so that the perimeter is now 20? Where would the new vertices be located?
Can you find the length of the rectangle without counting? Is there a way to calculate its length using the coordinates of the vertices? 
Instructional Implications If the student is not doing so already, encourage the student to interpret expressions of the form a – b as meaning the distance between two points whose coordinates are a and b or the distance from a to b on the number line. Provide the student with additional opportunities to represent distances between points with the same x or ycoordinates using absolute value symbols and to to determine the distance between them by counting. 