Codebusters Test Data-Driven Instruction 3

Question 1

In Codebusters, a student applies frequency analysis to a 40-letter ciphertext and gets unreliable results. Why is a short ciphertext problematic for frequency analysis?

Accepted Answer

Small samples deviate significantly from expected letter frequencies due to statistical noise

Answer

Short ciphertexts always use Vigenère ciphers

Answer

Short ciphertexts cannot be substitution ciphers

Answer

Frequency analysis only works on numeric codes

Question 2

A teacher tracks that students often confuse the Kasiski test purpose. What does the Kasiski test help determine?

Accepted Answer

The likely key length of a Vigenère cipher by finding repeated ciphertext segments

Answer

The substitution alphabet used in a Caesar cipher

Answer

The number of transpositions applied to a message

Answer

The plaintext word boundaries in a running key cipher

Question 3

Using data from competition results, a coach identifies that students struggle with consonant frequency ordering. In English, which group lists high-frequency consonants correctly?

Accepted Answer

T, N, S, R

Answer

Z, Q, X, J

Answer

V, K, W, Y

Answer

B, C, G, P

Question 4

A student analyzes error data and learns that single-letter words in aristocrat ciphers are highly diagnostic. Which two letters can appear as single-letter words in English?

Accepted Answer

A and I

Answer

E and O

Answer

I and O

Answer

A and E

Question 5

A Codebusters instructor reviews data showing students use frequency analysis but forget to check digraph patterns. What is the second most common digraph in English after 'TH'?

Accepted Answer

HE

Answer

ER

Answer

IN

Answer

AN

Question 6

After test analysis, a coach finds students misapply data-driven strategies when nulls are present. What is a 'null' in a cipher message?

Accepted Answer

A character inserted to mislead cryptanalysts that has no meaning

Answer

A letter that represents a space

Answer

The key letter in a Vigenère tableau

Answer

A cipher that encodes only numbers

Question 7

A data dashboard shows that a class underperforms on Patristocrat ciphers compared to Aristocrats. What key feature distinguishes a Patristocrat from an Aristocrat?

Accepted Answer

Patristocrats present ciphertext without spaces between words

Answer

Patristocrats use numeric symbols instead of letters

Answer

Patristocrats always use a Vigenère tableau

Answer

Patristocrats include punctuation but no letters