Grade 8 Math: Extend Sequence of Figures
A: Numbers of Triangles
Correct Response
Incorrect Responses
 18 and any number other than 32
 18 and no numerical response for the 4th figure
 Other incorrect
B: Number of Triangles in Figure 7
Correct Response
Incorrect Responses
 49 [Multiplies 7 x 7]
 58 [Series is 2, 8, 18, 28, 38…7th term
is 58]
 Other incorrect
C: Explanation for Extending to the 50th Figure
Correct Responses
 Correct general (i.e., literal) expression, e.g., 2n2 ,
or equivalent expressed in words
 2 x 502 OR 2 x 50 x 50 OR
100 x 50 OR (50 + 50) x 50 OR equivalent expressed in words
(disregard errors in computation)
Partial Responses
 Derives answer (5000) without showing work
 Other partially correct
Incorrect Responses
 50 x 2 OR 100
 50 x 50 OR 2,500
 Other incorrect
