Skip to content

Activity 001: Glass Type Identification and Property Matching

Activity ID: U12M1-ACT-001 Duration: 35 minutes

Overview

Students examine labeled and unlabeled samples of different glass types and use physical tests, reference data, and observation to identify each type and match it to its properties. This activity reinforces the connection between glass chemistry and observable characteristics, building the material science intuition needed for informed glass selection in later modules.

Materials & Equipment Needed

  • 8-10 glass samples (labeled set and unlabeled set):
  • Soda-lime glass (window glass, bottle glass)
  • Borosilicate glass (Pyrex lab beaker fragment, borosilicate rod)
  • Lead glass (crystal stemware fragment — handle with nitrile gloves)
  • Fused silica (if available; otherwise use photo reference)
  • Kitchen scale (0.1g precision)
  • Ruler or calipers
  • Glass Types and Properties Reference sheet (Student Material)
  • Mohs hardness test kit (or steel nail, copper penny for approximate testing)
  • Nitrile gloves (for lead glass handling)
  • Safety glasses
  • Activity worksheet (provided below)

Instructions & Procedure

Part 1: Labeled Sample Examination (10 minutes)

  1. Distribute the labeled glass sample set to each workstation
  2. Students examine each labeled sample, noting:
  3. Visual appearance (clarity, color, brilliance)
  4. Weight relative to size (heft test — lead glass is noticeably heavier)
  5. Surface hardness (scratch test with provided materials)
  6. Sound when tapped gently with a pencil (lead crystal rings; soda-lime thuds)
  7. Students record observations in the "Known Samples" section of their worksheet

Part 2: Unknown Sample Identification (15 minutes)

  1. Distribute the unlabeled glass sample set (3-4 pieces)
  2. Using the same observation techniques and the Properties Reference sheet, students identify each unknown sample
  3. For each unknown, students must:
  4. Record at least three observations
  5. State their identification with reasoning
  6. Identify the CTE value and note which other glass types it would be compatible with for fusing

Part 3: Application Matching (10 minutes)

  1. Present five application scenarios (written on board or handout):
  2. Stained glass window panel
  3. Laboratory beaker for heating chemicals
  4. Kiln-fused decorative bowl
  5. Torch-worked glass bead jewelry
  6. Budget classroom mosaic project
  7. Students select the best glass type for each application and justify their choice using CTE, cost, workability, and safety considerations

Discussion Points

  • Why can't you identify glass type by appearance alone at room temperature?
  • What physical property is the fastest identifier of lead glass vs. soda-lime?
  • Why is CTE the most critical property when selecting glass for a fusing project?
  • What safety considerations change when working with lead glass vs. soda-lime?
  • How does the "ring test" (tapping) work, and what does it tell you about atomic structure?

Expected Outcomes

  • Students correctly identify at least 3 of 4 unknown glass samples
  • Students demonstrate understanding of the relationship between composition and properties
  • Students can justify glass type selection for specific applications using quantitative data (CTE, hardness, density)
  • Students recognize lead glass as a special-handling material requiring additional safety precautions

Assessment Rubric

Criteria Excellent (4) Proficient (3) Developing (2) Beginning (1)
Sample identification 4/4 unknowns correct with reasoning 3/4 correct with reasoning 2/4 correct, partial reasoning 1 or fewer correct
Property matching All properties accurately linked to glass type Most properties correctly matched Some correct matches, some errors Significant confusion between types
Application scenarios All 5 correct with CTE/safety justification 4/5 correct with justification 3/5 correct, limited justification Fewer than 3 correct
Safety awareness Identifies lead glass hazards unprompted Identifies hazards when asked Partial awareness of lead hazards No awareness of material-specific hazards

Safety Considerations

  • Wear safety glasses throughout the activity — glass edges may be sharp
  • Wear nitrile gloves when handling lead glass samples
  • Do not drop or strike glass samples (fracture risk, sharp edges)
  • Handle all glass samples by edges, not by gripping flat surfaces (risk of slipping)
  • Dispose of any chipped or broken fragments in the glass waste container, not regular trash
  • Wash hands after handling lead glass, before eating or touching face

Last Updated: 2026-03-19