
ESCOT Problem of the Week: Archive of Problems, Submissions, & Commentary 
Try Earthquake 1 before you do this problem.When their teacher gives the okay, Sally and Suzie (who rides more slowly) hop on their bikes at school and ride to the emergency shelter, passing a house along the way.
 Explain the meaning of the red, purple, and green lines, as well as the red line segment described above.
 Suppose that Suzie passes the house 10, 20, or 40 minutes later than Sally. Read the graph to find out how far the house was from the school in each case.
 (Bonus) Write an expression (a distance, rate, time function) that allows Sally to find out how far the house was from the school, if she knows only the time difference between when she and Suzie passed the house. Please explain how you came up with the expression.
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Students did not completely respond to all of the parts of question 1. Many skipped explaining the "red line segment." Since this was vital to understanding the complete problem, it was necessary for the mentors to point this out and have the students revise and add their thoughts. Occasionally, when the other answers obviously pointed out that the students understood the red line segment's significance, the answer was counted as correct even if they skipped that one part of question 1.Often students did not seem to draw on their experiences with Earthquake 1 to respond to Earthquake 2. This was evident because they should have started using the term "rate" or "speed," and instead they were still using a more indirect description of that concept.
Students had difficulty seeing the "2.5" value. It might have been helpful to ask questions in decreasing values because it was easier to see the 10 miles for a difference of 40 minutes and the 5 miles for a difference of 20 minutes than it was to see the 2.5 miles for a difference of 10 minutes.
Once students got those exact pairs of numbers, they could see the relation and come up with an answer for the bonus question. It was common, however, for them to use the equation
d = 4x rather thand = 1/4x. Students had difficulty transitioning between the different forms of d=rt. (In other words, they were less familiar with r=d/t and t=d/r.)As was pointed out in the comments on Earthquake 1, the use of the term "expression" in the bonus question should have been "equation." This would have been less confusing.

Page Week 2 Answer these questions: 1. Explain the meaning of the red, purple, and green lines, as well as the red line segment described above: The red line is how the distane Sally and Suzie have traveled. The purple line Suzie's rate of riding. The green line is the rate of Sally's riding. The red line segment described above represents the diffrence of rate between the two girls. 2. Suppose that Suzie passes the house 10, 20, or 40 minutes later than Sally. Read the graph to find out how far the house was from the school in each case: 10 minutes: 2.5 miles 20 minutes: 5 miles 40 minutes: 10 miles 3. (BONUS) Write an expression (a distance, rate, time function) that allows Sally to find out how far the house was from the school, if she knows only the time difference between when she and Suzie passed the house. Please explain how you came up with the expression. d=distance r=rate t=time d=rt 2.5=r10 r=1/4 5=r20 r=1/4 10=r40 r=1/4 d=1/4t So after substituting the distance and time into the d=rt equation we found that ther was a 1/4 rate. So r=1/4. 

Page Week 2 Answer these questions: 1. Explain the meaning of the red, purple, and green lines, as well as the red line segment described above: red one is how far house is from school, purple one is sally's rate and greeen one is suzy's rate. the red line between the gren and purple is the amount of time faster sally is than suzy 2. Suppose that Suzie passes the house 10, 20, or 40 minutes later than Sally. Read the graph to find out how far the house was from the school in each case: 10 minutes is 2.5 miles, 20 miutes if 5 miles, and 40 minutes is 10 miles. 3. (BONUS) Write an expression (a distance, rate, time function) that allows Sally to find out how far the house was from the school, if she knows only the time difference between when she and Suzie passed the house. Please explain how you came up with the expression. time divided by 4= distance in miles. the paterns in number 4 all equaled four (10/4=2.5, 20/4=5 and so on 

Page Week 2 Answer these questions: 1. Explain the meaning of the red, purple, and green lines, as well as the red line segment described above: The red line shows the distance that the house is from the school. The purple is the rate at which sally rides. The green line represents suzi's rate. The red line segment shows the difference in time that it takes for suzi and sally to reach the house. 2. Suppose that Suzie passes the house 10, 20, or 40 minutes later than Sally. Read the graph to find out how far the house was from the school in each case: 10= the house is 2.5 miles from the school. 20= the house is 5 miles from the school. 40= the house is 10 miles from the school. 3. (BONUS) Write an expression (a distance, rate, time function) that allows Sally to find out how far the house was from the school, if she knows only the time difference between when she and Suzie passed the house. Please explain how you came up with the expression. The time difference divided by 4 equals the distance the house is from the school. t divided by 4= D We looked for patterns in #2 and found that distance in miles is 1/4 of the time difference. 
Alex B., age 12  Issaquah Middle School, Issaquah, WA
Amber B., age 13  Issaquah Middle School, Issaquah, WA
Christine B., age 13  Issaquah Middle School, Issaquah, WA
Jeff B., age 13  Issaquah Middle School, Issaquah, WA
Keturah B., age 13  Frisbie Middle School, Rialto, CA
Marissa B., age 13  Issaquah Middle School, Issaquah, WA
Allen C., age 12  Issaquah Middle School, Issaquah, WA
Allison C., age 12  Issaquah Middle School, Issaquah, WA
Jack C., age 13  Issaquah Middle School, Issaquah, WA
Katie C., age 13  Issaquah Middle School, Issaquah, WA
Katie D., age 13  Issaquah Middle School, Issaquah, WA
Chris G., age 14  Issaquah Middle School, Issaquah, WA
Bryant H., age 13  Frisbie Middle School, Rialto, CA
Phillip H., age 13  Issaquah Middle School, Issaquah, WA
Katelyn J., age 13  Issaquah Middle School, Issaquah, WA
Ashok K., age 13  Issaquah Middle School, Issaquah, WA
David L., age 13  Issaquah Middle School, Issaquah, WA
Derek L., age 13  Issaquah Middle School, Issaquah, WA
Sean M., age 13  Issaquah Middle School, Issaquah, WA
Christina R., age 13  Issaquah Middle School, Issaquah, WA
Sean R., age 13  Issaquah Middle School, Issaquah, WA
Jayna S., age 14  Issaquah Middle School, Issaquah, WA
Matt S., age 13  Issaquah Middle School, Issaquah, WA
Paradie S., age  Issaquah Middle School, Issaquah, WA
Scott S., age 14  Issaquah Middle School, Issaquah, WA
Yusra S., age 13  Issaquah Middle School, Issaquah, WA
Jesse T., age 13  Issaquah Middle School, Issaquah, WA
Johanna T., age 14  Issaquah Middle School, Issaquah, WA
Ella W., age 13  Issaquah Middle School, Issaquah, WA
Kirsten W., age 12  Issaquah Middle School, Issaquah, WA
Matthew W., age 13  Issaquah Middle School, Issaquah, WA
Brian Y., age 14  Issaquah Middle School, Issaquah, WA