IB Computer Science HL · Year 2 · Lesson 26
BST operations, traversal and evaluation
Abstract data types separate what operations mean from how they are implemented, helping you choose structures by behaviour and trade-offs.
Paper 250 minutesB4.1.4
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Today’s targets
What you need to be able to do
2 / 7
- ExplainThe structures and properties of BSTs
- RetrieveReconnect today’s new material to previously taught content from this topic.
B4.1.4
Paper 2 lensMatch the depth of every response to the command term. Previously learned content can move quickly, but retrieval must still be accurate.
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Retrieve
Rapid Recall Deck
3 / 7
Say the answer aloud before flipping. Mark secure knowledge quickly and spend time on the gaps.
- What does an in-order traversal of a correctly ordered BST produce?: The stored values in sorted order.
- What are the three main BST deletion cases?: Deleting a leaf, deleting a node with one child, and deleting a node with two children.
- How can a highly unbalanced BST affect performance?: Its height can approach the number of nodes, causing search/insert operations to behave more like a linear structure.
- What determines the path followed during a BST search?: Each comparison with the current node determines whether the search continues into the left or right subtree.
- Why is tree height important to BST efficiency?: Search, insertion, and deletion follow paths through the tree, so shorter paths generally require fewer comparisons.
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B4.1.4 · Learn
Core knowledge and application
4 / 7
B4.1.4Explain
The structures and properties of BSTs
Abstract data types separate what operations mean from how they are implemented, helping you choose structures by behaviour and trade-offs.
Exam moveGive the mechanism or relationship and make the reasons/causes explicit.
Required detail 1How binary search trees (BSTs) are used for data organization
Required detail 2Insert, delete, traverse and searching nodes in a BST
Required detail 3Sketching a BST as a tree diagram
Assessment boundaryPaper 2
Explain it without notes
Explain: The structures and properties of BSTs in the context of a system that needs efficient insertion, search and set membership.
- How binary search trees (BSTs) are used for data organization
- Insert, delete, traverse and searching nodes in a BST
- Sketching a BST as a tree diagram
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Apply
Transfer to a new scenario
5 / 7
ScenarioA system that needs efficient insertion, search and set membership needs a design or technical decision related to today’s topic. Explain what matters and why.
- How binary search trees (BSTs) are used for data organization
- Insert, delete, traverse and searching nodes in a BST
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Exam lens
Paper 2 practice
6 / 7
Build the response before checking notesUse precise terminology and match the required depth.
- Explain: The structures and properties of BSTs in the context of a system that needs efficient insertion, search and set membership.
Self-checkAnswer the exact command term. For explain, include mechanism/reason; for compare, pair criteria; for discuss/evaluate/justify, build supported reasoning and a conclusion.
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Homework
Finish the learning cycle
7 / 7
IA — main task
Continue Criterion D development. Keep code readable, record meaningful implementation decisions, and maintain testing/evidence notes as you work.
Syllabus — short
Complete one targeted Paper 2/Paper 1 retrieval task from today’s lesson.
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End of Lesson 26.