Cool-Water Design Investigation — Student tasks

Start here: choose a route

Target: use matched fresh trials to compare thermal protectors, change a design, and revise a claim. Intended for Grade 6; relevant standards are in the Grades 6–8 band.

Practical route

Work under teacher supervision. Read the design brief through instruments and trial order. Record your phase’s instrument checks at instrument-check record. Run three first comparisons using the first-comparison trial 1–3 record forms. Compare results at compare the first trials. Read commit to a redesign and run three retests using the retest trial 1–3 record forms; finish the Reassess the Redesign and Evidence and Explanation tasks.

Supplied-data route

No equipment is needed. These are fictional constructed records, not measurements from this class. Read the brief and procedure; use only the supplied first-comparison record and compare the first trials. Write and retain your proposed redesign before opening the supplied redesign/retest record. Then use that record to reassess the redesign, complete evidence and explanation, and use a different later check when your teacher gives it to you.

Ways to respond

Write, dictate, explain orally to a recorder, or use a labeled sketch/table. Give the same quantities, comparison conditions and evidence in any format. Graph drawing is optional.

Water is not for drinking. Keep cups in spill trays. Do not heat, cut, puncture or modify equipment. Tell the teacher about spills, leaks, damaged equipment or an unstable cup.

the design brief

Design a removable dry sleeve that may slow the warming of 150 mL of cool water in a covered plastic cup for 10 minutes in a classroom. This is a classroom comparison; it makes no promise about refrigeration, food, medicines or a particular final temperature.

The original sleeve uses one supplied 26 cm × 6 cm felt sheet, at most 3 mm thick. Baseline bare cup has no sleeve. The redesigned sleeve may use at most two supplied sheets total and at most 30 cm of tape. Its footprint must fit within a 12 cm diameter circle; its height must be at most 9 cm. Do not cover the base, top cover, probe slot or display.

Performance aim: look for less warming than the identified reference in comparable trials. A small or inconsistent difference can leave the result inconclusive. There is no numeric thermal pass mark.

assemble and label

Use the three matching cups and loose covers checked and supplied by your teacher: one bare reference, one original sleeve and one redesign. The teacher checks that supported probes fit through the existing slots without cutting. Covers stay loose, not sealed or pressurized. Ask the teacher if the sleeve does not wrap with overlap or the sensing region cannot stay fully immersed at the marked depth.

1. Put bare cup and original sleeve in separate marked positions in one dry spill tray, about 15 cm apart, away from sunlight, vents and electrical equipment. Keep them there during a run.
2. Wrap one dry 26 × 6 cm sheet around the cup used for the original sleeve. Center it vertically: approximately 1 cm of wall remains bare above and below. Overlap the seam; use two pre-cut 5 cm tape strips to hold the sleeve. Keep the reference cup bare. Leave both cup bases directly on the same tray surface.
3. Fit identical covers. Support probes vertically through the existing slots using the teacher-supplied holder. The sensing region must be fully immersed, centered horizontally, with its tip 1.5 cm above the inner base, not touching any wall or base. Mark/check insertion depth with the teacher.

Text equivalent of the setup: left and right cup on one level tray; equal water depth; identical covers and centered probes; bare cup; original sleeve around side wall only. Probe displays remain dry and readable.

Check the apparatus before starting

Draw your pair below, or describe it using a response method your teacher offers. Label water, sleeve, cover, probe and exposed base; explain one condition that must match.

run a matched pair

Use two suitable non-glass liquid probes with 0.1 °C displays, checked by the teacher for water immersion, temperature range and response instructions. Display steps do not establish accuracy. A separate classroom instrument records room air at cup height.

Standard conditions: room air 20–24 °C; common gently mixed cool-water batch 12–14 °C. Measure 150 mL into each cup using the same marked measure, within 2 mL. No ice goes into cups. Record the actual conditions.

Put probes at the marked depth and covers in place. Wait for the teacher-checked response interval (at least 60 seconds). Read both. Starts must differ by no more than 0.5 °C, both be 12–14 °C, and room must be at least 6 °C warmer. If not, keep the readings, mark a failed start, and ask for a fresh matched pair.

When both starts qualify, record both 0-minute readings and the actual clock time; start the timer. Record both probes at 5 and 10 minutes, within 15 seconds of each other and the target time. Record actual time if late. Keep probes in place; do not stir, move cups, lift covers or handle sleeves during a run.

Record room air at 0 and 10 minutes, missing readings, spills, movement and wet sleeves. A room shift over 1 °C, a missing 0/10 reading or a changed procedure flags an inconclusive comparison; retain it and repeat with fresh water if time permits.

After each run, retain the reading sheet. Teacher drains cups, checks sleeve dryness, and conditions cup interiors with 150 mL room-temperature water for 5 minutes. Drain and dry interiors before fresh cool water. Keep sleeves assembled and dry between runs; log any rebuild. Three timepoints are ONE trial. Three trials require three fresh water pairs.

instruments and trial order

Before each phase, the teacher places probes A and B together in stirred common water, first at room-water temperature and then at cool-batch temperature. Hold equal immersion depths without contact. Wait the maker’s response interval and at least 60 seconds; then read twice 30 seconds apart. Each probe must change no more than 0.2 °C between these readings and their displayed readings must differ no more than 0.5 °C. If not met within 2 minutes after the minimum response interval, replace/check equipment or use supplied data. Record all readings.

This is a consistency/response check, not calibration or proof of accuracy. Do not silently correct readings by subtracting an assumed offset. Repeat the check after the phase; a new disagreement flags possible drift.

First comparison order: F1: bare cup left/A, original sleeve right/B. F2: bare cup right/B, original sleeve left/A. F3: bare cup left/A, original sleeve right/B. Labels follow cups, not position. Teacher moves empty cups and swaps probes between trials, never during a run. This reduces a one-position or one-probe explanation but three trials do not perfectly balance everything.

instrument-check record

BLANK empirical form. Use one copy for each group/phase, or attach a clearly identified teacher-recorded check for your exact probes. Follow the instrument-check directions on the Instruments and Trial Order page. Keep before and after values. This checks consistency and response, not calibration.

Record actual check timestamps, conditions, replacement instrument IDs and action here or on an attached named note. Link every run to its check ID. If instruments are replaced mid-phase, use a new check record and fresh samples.

First comparison · trial 1

Blank empirical record. Run F1; reference: bare cup; prototype: original sleeve with one dry felt sheet. Use the fresh-pair procedure and instrument-check directions on the Instruments and Trial Order page. Record °C exactly as displayed; never invent a missing reading.

First comparison · trial 2

Blank empirical record. Run F2; reference: bare cup; prototype: original sleeve with one dry felt sheet. Use the fresh-pair procedure and instrument-check directions on the Instruments and Trial Order page. Record °C exactly as displayed; never invent a missing reading.

First comparison · trial 3

Blank empirical record. Run F3; reference: bare cup; prototype: original sleeve with one dry felt sheet. Use the fresh-pair procedure and instrument-check directions on the Instruments and Trial Order page. Record °C exactly as displayed; never invent a missing reading.

supplied first-comparison record

CONSTRUCTED FICTIONAL RECORDS. Constructed for analysis; no physical run or computational simulation produced these values.

Shared conditions: identical described cups/covers, 150 mL each, dry one-sheet original sleeve, probes as scheduled, minimum response 60 s. Fictional consistency checks: room A/B22.0/22.1 then 22.0/22.1 °C; cool 13.0/13.1 then 13.0/13.1 °C before and after phase. No spills or movement. Starts/clock/room readings appear below; date: fictional Day 1.

F1 bare cup left/A; original sleeve right/B. F2 bare cup right/B; original sleeve left/A. F3 bare cup left/A; original sleeve right/B. Each run used fresh water after the stated room-water reset.

compare the first trials

Use your F1–F3 records, or the constructed first-comparison records in the supplied first-comparison record. Temperature rise = 10-minute reading minus 0-minute reading. For each usable pair, compare the two rises; a smaller rise means less warming during that interval.