OAE Computer Science case studies
OAE Computer Science · Put your knowledge to work in context.
Computer Science (054) is the Ohio Assessments for Educators (OAE) licensure test for candidates seeking an Ohio educator license with a computer science field. It appears on the official OAE assessment list as "054 Computer Science" and replaced the earlier Computer Information Science assessment, which the program listed for testing only through 12/15/19. The OAE Computer Science case studies are 5 cases and about 4,446 words.
1Two's-Complement Negation and an Over-Tight Float Tolerance in a Cold-Chain Logger
A cold-chain monitoring product stores each chamber temperature as a signed 16-bit integer in hundredths of a degree Celsius, and each humidity reading as an IEEE-754 binary32 fraction of relative humidity. Two defects surface during release validation.
875 words, about 4 min2A Mutable Default Argument That Only Bites on a Live Worker
A payments service exposes a Python function def add fee(items, fee, ledger=[]) that appends a fee record to ledger and returns it. Under load, fee records from one customer's transaction appear on another customer's receipt, roughly 3 times per 10,000 requests, always on the same worker process, and only after that worker has handled a refund.
840 words, about 4 min3Sizing a Bloom Filter Under a Hard 1 GiB Cap
A log pipeline must drop duplicate event IDs before aggregation. Events arrive at a steady 15,000/s for a 6-hour nightly window, IDs are random 64-bit values, and about 4% of events duplicate an ID seen earlier in the same window.
940 words, about 5 min4502s From a Keep-Alive Race and Three Cookie Findings
A SaaS team runs a stateless Python API behind a cloud load balancer that terminates TLS and forwards plain HTTP to three application instances. After a traffic increase, users report intermittent 502 responses - roughly one every 90 seconds per instance - always on connections that have been idle for about a minute, and the application logs show no corresponding request at all.
880 words, about 4 min5Overselling Seats With a Per-Process Mutex
A small-venue ticketing service tracks inventory in a single database row, seats remaining . The purchase path reads the row, checks remaining = qty , then writes remaining - qty , with the whole read-check-write wrapped in an in-process mutex.
911 words, about 5 min