SUNY Geneseo Department of Mathematics
Wednesday, September 29
INTD 105 17
Fall 2021
Prof. Doug Baldwin
(No.)
Formative vs summative evaluations: because of how my mastery grading scheme averages only recent and high grades to get “the” grade for each learning outcome, individual grades on essays and drafts are more feedback to you about how you’re doing on various learning outcomes (so-called “formative” assessments) than they are permanent judgements about you passing or not passing the course (so-called “summative” assessments). Most likely, particularly if the grades in question are low, they will get pushed out of the averages before final grade time.
Redos: My mastery grading scheme also offers the possibility of redoing graded exercises in order to get more practice with their learning outcomes, and to get grades that reflect that additional practice (again, assuming additional practice translates to higher grades, those grades will tend to replace earlier ones in your averages). I have been thinking that the typical “redo” in this course would involve writing an additional revision of an essay beyond the “final” one, but some people have asked if it’s possible to redo a draft. The answer is “yes.” You can grade a draft with me, then write a second draft and discuss it with me as a “redo,” and then go on to write a final draft. (And conceivably “redo” that also in a fourth draft.)
Based on “Substitution” and “Codes, Ciphers, and Keys” in Simon Singh’s “Black Chamber” web site.
Substitution ciphers encrypt by replacing each letter of the alphabet with some other letter or symbol to form the ciphertext.
The “key” is the rule for pairing plaintext letters with ciphertext symbols.
In general, the more possible keys a cipher has, the harder it is to break.
There are variations on the basic substitution strategy, e.g., having a few ciphertext symbols that stand for common words instead of for letters, having “null” symbols that don’t stand for any plaintext character but can be sprinkled around a ciphertext to break up patterns in it, etc.
Try, either individually or with a neighbor or two, creating your own substitution cipher.
Put your key into a Google document, then use the same document to leave encrypted messages for other groups.
Breaking substitution ciphers.
Please read “Cracking the Substitution Cipher” and its subsections at the Black Chamber web site.