Distinguish a Membership Test from an Index
Check whether the queried value exists anywhere in the supplied collection.
About 18 minutes, plus any extended practice
Open lesson 1Work with Collections and Defensive Inputs
Given counts={"A":4,"B":7}, retrieve B and test whether 7 appears in[4,7]. Design a 0–10 integer input rule and explain why an alias is not an independent backup.
Before you begin
- Read list and dictionary literals and compare integers.
Choose by skill rather than age alone. Read with an adult when useful, revisit a lesson, or explore another grade.
Follow the lesson sequence
Use a Dictionary Key to Retrieve a Value
Look up the exact supplied key and report its associated value.
About 18 minutes, plus any extended practice
Open lesson 2Validate at the Input Boundary
Check type and range before accepting a count into the stated workflow.
About 18 minutes, plus any extended practice
Open lesson 3Preserve an Original before a Transformation
Compare the source before/after record and distinguish a new result from a mutation.
About 18 minutes, plus any extended practice
Open lesson 4Review and transfer
After the lessons, try 4 new review cases and a practical task. Each answer has an explanation and a link back to the related lesson.
Open the unit reviewGuest answers are temporary. Keep your own paper or document; this unit does not certify completion or record a school grade.
Topic references
- 2026 CSTA PK–12 Computer Science Standards: topic reference — Programming; Systems & Security
These references informed the topic selection. They do not certify complete standards alignment.