RockLicker · Grade 3 · Lesson 1 of 5

Three Clues, One Candidate

Compare multiple properties to choose a supported mineral candidate from a short list.

  • Grade 3
  • 35 minutes
  • Worksheet + teacher guidance
Back to Grade 3

What you will learn

Color is useful to describe but can vary within a mineral. Several independent properties give a stronger comparison than one surface clue.

Words to use

  • luster: how light reflects
  • hardness: resistance to scratching
  • candidate: a possible match

Evidence for this lesson

Candidate table: Quartz—glassy, hardness 7, often curved fracture. Fluorite—glassy, hardness 4, four cleavage directions. Muscovite mica—thin sheets, hardness about 2–2.5. Mystery: purple, glassy, measured hardness 7, curved fracture surfaces.

Use the supplied record as written; do not invent missing results.

Work through the activity

  1. 5 min · Learn the cluesRead the candidate table. Point to hardness and luster; explain why both quartz and fluorite can look purple.
  2. 10 min · CompareUnderline the mystery clues. Cross out candidates with a conflicting hardness or surface structure. Keep a candidate only if it fits the combined evidence.
  3. 10 min · ExplainWrite a working match with two reasons. Tell a partner which clue was least useful and why.
  4. 10 min · Test the limitImagine that hardness was never measured. Discuss how the list of candidates changes and what safe next observation would help.
RockLicker
GRADE 3 · LESSON 1

Three Clues, One Candidate

Draw on the printed sheet or write, type or dictate your response.
Draw on the printed sheet or write, type or dictate your response.
Draw on the printed sheet or write, type or dictate your response.
Draw on the printed sheet or write, type or dictate your response.

Responses stay in this open page only. Print before closing or changing pages; no student record is stored online.

Check your understanding

Which clue separates the purple candidates most clearly here?

Teacher & family guide · answers and assessment

Grade 3 · Three Clues, One Candidate

Learning goal: Compare multiple properties to choose a supported mineral candidate from a short list.

Expected responses

  1. Quartz best fits the supplied description.
  2. Hardness 7 and glassy luster support quartz; curved fracture also helps.
  3. Both quartz and fluorite can be purple.
  4. Color and glassy luster alone leave more than one candidate; a further property is needed.

Understanding check: Hardness 7 versus 4. Both may be purple, but the supplied hardness values differ.

Watch for this misconception

A matched classroom card does not confirm the identity of every similar real specimen.

Assess the evidence

Look for the observations, calculation or explanation named in the learning goal. Accept accurate drawings and dictated responses. Use the expected responses to discuss reasoning; a correct guess without explanation is a starting point for another conversation.

Adapt and extend

Read prompts aloud, enlarge print or let a partner record the learner’s explanation. Try all five cases in Mineral Detective and explain one rejected candidate.