Six Unlabeled Swatches: Which Ones Did Nature Make?

Investigation question: Using only property tests you can run on a desk, which of six unlabeled fabric swatches are made of natural fibers and which are synthetic, and which test gives the most trustworthy evidence?

Your role today

• Tester: Runs each test exactly the same way on every swatch: same drop size, same soak time, same crumple grip, same lens.
• Timer and measurer: Times the water drop and the soak, reads the balance, and calls out every value before anyone interprets it.
• Recorder: Writes every value in the evidence table as it is called out, and fills the verdict table only after all four tests are finished.
• Skeptic: Challenges every verdict with 'which test says so?' and makes sure each swatch has at least two pieces of evidence behind it. Keeps the group from deciding by feel or color.

Safety

• No flames anywhere in this lab. The fabric burn test is deliberately not used: synthetic fibers melt and drip, and the fumes from burning acrylic and nylon are harmful. Tell students not to try it at home.
• Water on hard floors is a slip hazard; keep the soak tray on a paper towel and wipe spills at once.
• Jute and burlap shed coarse fibers that can irritate eyes; do not rub eyes after handling it, and wash hands at the end.
• Tweezers are pointed; pull fibers at desk level, pointed away from faces.
• Some students are sensitive to wool; anyone with a known wool allergy handles swatch C with a paper towel or lets a partner run that test.

Procedure

1. Lay the six squares out in letter order. Do not guess yet. Each person writes one prediction in q1 of how many of the six are natural, without discussing it.
2. Water-drop test. The tester places one drop of water in the center of square A from a height of about 1 cm. The timer starts at once and stops when the drop has fully soaked in and no shine remains, up to a limit of 120 seconds. Record the time; if the drop is still beaded at 120 s, record 'over 120 s, beads'. Repeat for B through F, same drop size, same spot on the square. Blot each square dry and set it aside.
3. Soak-and-weigh test. Weigh strip A dry and record its mass to 0.1 g. Lay it flat in the tray of water for 60 seconds, lift it with tweezers, hold it above the tray for 30 seconds so loose water drips off, then weigh it again. Record the wet mass. Repeat for B through F. Compute the percent gain for each: (wet mass minus dry mass) divided by dry mass, times 100.
4. Crumple test. Using the dry squares, the tester crushes square A into a tight ball in a fist for 30 seconds, then opens the hand and lets the square lie flat without smoothing it. After 60 seconds, the group rates the wrinkles from 0 (no creases) to 3 (sharp creases everywhere). Repeat for B through F with the same grip.
5. Fiber look. With tweezers, pull three or four fibers from a cut edge of each square. Look at them against a dark surface with the hand lens. For each swatch record: are the fibers all the same thickness or do they vary? Are they smooth and shiny or dull and uneven? Are they straight, crimped or wavy? Are they long and unbroken or short? Sketch two contrasting swatches in the drawing box.
6. Fill in the evidence table completely before anyone argues a verdict. The skeptic checks that every cell has a value.
7. Verdicts. For each swatch, the group decides natural or synthetic and writes the two strongest pieces of evidence and a confidence rating (sure, fairly sure, guessing). The skeptic must hear a test named for every verdict; 'it feels fake' does not count.
8. Only when the verdict table is complete, open the envelope. Record the real identities and mark each verdict right or wrong. Then answer q2 and the analysis questions individually.
9. Optional if time allows: lay the six wet strips flat on paper towels at the same time and check them at the end of the period. Record which are dry to the touch and which are still damp.

Record your observations

Lab 1 recording sheet: Six unlabeled swatches

Fill in every cell of the evidence table before your group decides anything. The verdict table is completed only when all four tests are done, and the identity column only after the envelope is opened.

Analysis questions