-Code Control, easily programmed at the keypad (19 user code capacity, with 10,000 possible user code combinations)

Is this claim true? 10,000 possible user code combinations?

Looking at this as a social studies question, I started with “Why would someone want this lock?”

Students: To keep people from jacking my stuff.
Teacher: Yeah, but aren’t people born as good human beings?
Students: Mostly no, a few yes.
Teacher: Insert discussion about Hobbes and Locke here.

Or if learning about the Bill of Rights:
Teacher: Can anyone break this down?
One Student: Yeah I could in a heartbeat.
Teacher: Ok, besides_____ who would want to break this down?
Students: Cops
Teacher: Why?
Students: Stop a crime… search…
Teacher: Doesn’t the person who owns this door want it to stay shut? Wouldn’t the framers of the constitution want it to stay shut?
Students: Yeah but…
Teacher: But what?
Students: What if they did something?

And begin discussion about 4th Amendment rights to privacy.

2) Wouldn’t it be easier and faster to break the window? Or are we assuming the window doesn’t exist?

3) Can you come up with an algorithm of guessing that does not use every combination but gets to “the one” faster than straight brute force method?

Personally, I think that this particular image lacks opportunities for inquiry. Perhaps it was presented with other kinds of door locks leading students to come up with and answer the question, “which is the most secure lock?”

What if a lock recognized 2-5-3-6 as also any of its permutations? Would this be a better lock? In other words suppose the combination was 2-5-3-6 but I input the sequence as 3-2-6-5 and the lock still unlocks. Does this make the electronic lock better or worse and why?

eg GpA guessed a 5 digit code right in 60 guesses,
group B guessed a 4 digit code right in 20 guesses –

The lack of iterative practice is my fundamental gripe with the lesson plans so far. The students need to be immersed in several different-but-similar situations to practice the skills they’ve learned. Your plan addresses that.

@Robert, this seems to me like a problem endemic, not just to WCYDWT? prompts, but to lecture-based pedagogy in general.

I can’t say I have the solution figured out, but whenever I deploy these media in class, I make it a goal to give each student (or groups of students) something tangible to manipulate, draw on, or work through on their own. Which helps.

Starter…
a few games of the old “mastermind” puzzle – show them the lock and tell the you are thinking of a 3 digit code. let them guess what it is, you just tell them how many digits are correct, and if they are in the right/wrong place
(eg. If i’m thinking 216 but they guess 613, i tell them they’ve got two correct, *but* one in the wrong place)
Use this to experiment, maybe keep a record of how many guesses we take. Play as a class or in pairs.
Work out our average number of guesses.

Main…
Determine from my simple game how many possible combinations there could be (depending on whether that last key is a “C” or a “0”, 9^3 or 10^3) Assume our average number of guesses is 12, what is the probability of getting it right within 12 guesses? 1% ish – how did we beat these ridiculous odds to get it right so quickly? Talk about logical deductions they made which took the element of chance out of the activity after a few guesses.

Offer them data on different sets of fictional guesses,
eg GpA guessed a 5 digit code right in 60 guesses,
group B guessed a 4 digit code right in 20 guesses –
who was better?

Finish…
Offer them a fake job where a Gang is offering $1,000,000 for an expert code cracker for a bank job. They need to be able to beat odds of 1%. The bank vault has a keypad [1-6] with a 10 digit code – would they hire someone who needed 1,000 guesses? 3,000?
how many guesses would you be able to have to get the job?

Homework: break into your dad’s safe, steal his stash of expensive cigars and bring them to teacher asap.

Thoughts?

What does the lesson actually look like?

What do we actually mean when we say “ask the students…”? How are they supposed to answer? By replying to you? In which case only one student at a time has a chance to speak and every thing they say is filtered by your response (including tone of voice and body language).

I don’t have a lesson plan, but I would definitely start by saying “take 2 minutes to consider in silence how long it would take to break in. Make notes.” Then say “Now take another 5 minutes to discuss in groups of 4 the same question. Prepare questions you would like to ask me at the end of the 5 minutes if you feel you need clarification.”

Not sure where it would go next :-)

I like the plan. Particularly the use of a dummy variable C for the combination. That’s fun. It isn’t particularly well-scaffolded, though, which most advanced students won’t mind but which will frustrate novices. I think it would be helpful to have novices write a program that will crack a 1-number combination, a 2-number combination, etc., building up to the general case. That might drive the advanced student nuts, however, which is why they call it differentiation.

I like the programming exercise, though it doesn’t use the image for much more than a visual hook or an inspiration. (Not that it needs to do anything more than that.) I’d like to see a definitive lesson plan for math and I’d really like the participants to think about they could modify the image to push the lesson forward.