Chicago Prison Escape
65
skips
skips
35
questions
questions
Act One
 1.
What is a guess that is too low?
 2.
What is a guess that is too high?
 3.
What is your best guess?
 4.
What factors may affect the accuracy of our answer?
Act Two
 ImageFull view of the prison building (escape was on the other side of the prison)
 ImageView of the rope coming out of the cell
 ImageDetailed view of how the sheets were weaved to make the rope
 ImageView of the rope as it approached the street.
 Imageâ€œRoof of a corridor that connects to an adjoining parking garageâ€
 Teacher noteThere are many assumptions that need to be made to solve this problem. Here are some to consider:
Distance from the prisonersâ€™ cell to the ground â€“ The cell is on the 17th floor and the video states that the rope â€œextends down about 15 stories and ends just a few feet shy of the roof of a corridor that connects to an adjoining parking garage.â€ The corridor appears to be about two stories tall, which matches 15 stories (17 stories â€“ 2 stories). Assuming prisons are like most buildings and that each story is approximately 10 feet high, then their rope descended about 150 feet.
Length of a bed sheet â€“ I am assuming that each sheet is approximately 6 feet long.
Based on those assumptions, I would expect studentsâ€™ first calculations to be something like (170 feet â€“ 20 feet) / 6 feet per sheet which gives an estimate of about 25 sheets.
Unsurprisingly, the exact number of sheets used has not been released by the prison. The best data I have comes from the article included in the â€œDownload filesâ€ link that cites â€œabout 200 feet of bed sheetsâ€. It isnâ€™t clear how the report came up with that estimate, so it is worth considering that your students may have come up with a more realistic estimate. Points to discuss to help students reflect on assumptions they may have incorrectly made include:
Dividing by 6 implies that the sheets are lined up end to end. Since they are obviously being tied together, the knots will use up some of the length.
Standard twin bed sheets are actually 75â€³ long. Long twin bed sheets are actually 80â€³ long.
Each floor may be taller than 10 feet (especially the first floor and ninth floors).
The prisoners may have made the rope more than one sheet thick. Visually the rope appears to be braided from strips of sheets rather than leaving the sheets intact. It looks like the sheets are at least two sheets thick.
A new calculation based on these assumptions is: (170 feet long x 2 sheets thick) / 5 feet of usable fabric per sheet is 68 sheets.
One other interesting factoid about this escape is that, according to Wikipedia, â€œeach cell has a slit window which is 5 inches wide by 7 feet long.â€ I do not know how someone was able to escape out of a window that narrow.
Lastly, thank you to Andrew Stadel for the suggestion to leave out the part of the video that states the prisoners escaped. As he mentioned, â€œstudents will be drawn to that question which allows you to discuss the details.â€ So, when the time is right you can share with students that both prisoners did escape.
Sequel
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How much money does the state save in land payments due to the prison being a highrise?

















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