2007-2008 Grade 8 Mathematics Item and Scoring Sampler

MATHEMATICS
Item #27
Top Scoring Response:
Part A Answer
Train L : 3 (hours)
Train M: 3.75 (hours) or
3 3 } (hours) or
4
3 hours and 45 minutes
Train L :
Support
d = r • t
225 = 75 • t
225
}
75 = 75t }
75
3 = t
Train M :
225 = 60 • t
225
}
60 = 60t }
60
3.75 = tmi
AND
(2 score points)
0.5 point for 2 correct times
1.5 points for complete support
Sample Explanation:
I used the distance formula (distance equals rate times time) for each
train. I put in 225 miles for the distance and then put in each train’s
speed. I then solved each equation for t to determine each train’s time
to travel 225 miles.
OR equivalent
Part B Answer
810 (miles)
Train L :
Train M :
Support
d = r • t
d = 75 • 6
d = 450
d = 60 • 6
d = 360
450 + 360 = 810
AND
(2 score points)
0.5 point for correct answer
1.5 points for complete support
Sample Explanation:
I put the trains’ time (6) and each train’s rate into the distance formula. By
multiplying rate times time, I found the distance each train traveled in 6 hours.
Then, since the trains are going in opposite directions, I added the distances together
to determine the total distance between them.
OR equivalent
Grade 8 Mathematics Item Sampler 2007–2008 39