Teacher's Guide

Learning objectives

• Explain Linear search and Worst case in the context of this lesson.
• Use the worked example to answer the three practice questions with supporting reasoning.
• Complete the activity, evaluate its result, and identify one limitation or possible improvement.

Prerequisites: Prior middle-school subject foundations, reading, and arithmetic; Foreign Languages begins introductory Spanish. Review prerequisites before assigning the activity.

Suggested time: Three to five 45-minute sessions, including activity development and review. Language units need brief repeated spoken practice between sessions.

Teaching sequence

1. Introduce: Present the title as a question or problem. Ask learners what they notice and record two initial ideas without treating them as established facts.
2. Explain: Read the concept section and teach the two vocabulary items. Ask learners to paraphrase the distinction between them using a concrete example.
3. Model: Work through the example. Identify given information, assumptions, and the reason for the result or interpretation. Use a teacher's spoken model for language pronunciation.
4. Apply: Complete the activity individually or in pairs. Require a draft, a check against the task, and a brief revision. Discuss why different justified responses may be acceptable.
5. Retrieve and evaluate: Answer practice and vocabulary questions independently; use the answer key for feedback. Finish with the reflection and an activity rubric.

Assessment and differentiation

The companion CSV contains five retrieval entries: two vocabulary questions and three practice questions. Award one point per accurate answer, accepting equivalent wording that preserves the meaning. Language answers may be oral or written according to the goal. Revisit missed concepts rather than using the score as the only measure of learning.

Assess the activity separately with four criteria, each scored 0-2: correct use of lesson concepts; clear evidence or reasoning; completion of the task requirements; and a useful revision or acknowledged limitation. A 0 indicates missing or unsupported work, 1 indicates partial achievement, and 2 indicates clear achievement. Accept multiple designs, interpretations, and decisions when their reasons meet the criteria.

Support learners with a word bank, annotated example, smaller first step, or partner rehearsal. Extend by changing one assumption or constraint and asking how the result would change. Use invented personal details in financial and social tasks. Optional school character discussion can connect honesty, respect, cooperation, and stewardship to the activity; assess the subject knowledge and reasoning separately.

Student Worksheet

Concept and helping material

Algorithm comparison separates correctness from resource use. A linear search examines elements until it finds a target or reaches the end. In a simple worst-case comparison-count model, its work grows proportionally with list length. The model does not directly predict elapsed time across devices or implementations.

Vocabulary

• Linear search: Checking items sequentially to locate a target or establish its absence.
• Worst case: The maximum resource use among inputs of a stated size under a model.

Worked example

Searching an unsorted list of 100 items for an absent target requires 100 item comparisons in the basic linear algorithm. Doubling the list doubles that worst-case count.

Investigation or design task

Trace linear search on two fictional lists. Count comparisons for first-position, last-position, and absent targets; explain what the count model omits.

Record your work: State the goal; show your drawing, dialogue, calculation, data, or argument; explain one choice; and describe one check or revision. Identify a limitation rather than claiming your work proves more than it does.

Practice

1. How many comparisons are needed for an absent target in 100 items?
2. Does a first-position match require the full 100 comparisons?
3. Does comparison count alone establish exact runtime on every device?

Vocabulary retrieval

1. Define Linear search.
2. Define Worst case.

Reflection

Choose one answer or activity decision. Explain the evidence, calculation, language pattern, or reasoning that supports it. Describe one change of context or assumption that could change your conclusion.

Answer Key

2. No. It can stop after one.
3. No.

Vocabulary answers are the definitions above and appear in the CSV. Activity and reflection responses vary; use the teacher rubric and require specific reasoning tied to the task. A different supported interpretation is acceptable where the question allows it.

Source Reference

Everything You Need to Ace Computer Science and Coding in One Big Fat Notebook, PDF viewer pages 121-122 (1-based). Conceptual background; the examples, calculations, questions, and activities here are original adaptations. These pages were inspected in the supplied file; viewer numbering may differ from printed numbering. No source worksheets or illustrations are reproduced.

Companion question CSV | Grade guide