No kiln, no clay delivery, five weeks left
A Grade 9 craft unit requires learners to hand-build a clay vessel using pinch, coil and slab techniques and to understand the stages of clay from greenware to glaze. The school has no kiln and no supplier will deliver clay because of transport costs; the nearest pottery is 90 km away. There is red clay soil on the school grounds, a budget of P400 for the whole term, 60 learners and five weeks left. The written paper includes questions on the leather-hard stage, bisque firing and glaze. Families cannot be asked for contributions. The head of department suggests replacing the unit with drawing, but the teacher wants to keep the craft outcome because portfolio evidence is required. The science teacher has offered the use of a covered outdoor area and a fire extinguisher.
1. Decide whether to replace or adapt the unit, and justify the decision against the assessment criteria. Then set out the practical steps for testing and using the local clay, including firing.
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Replacing with drawing would be a validity error. The construct is hand-building: pinching, coiling, slabbing, joining, and understanding the stages of clay. Drawing cannot evidence it, so a drawing unit would leave the portfolio requirement unmet and would misrepresent what learners can do. 'Fired' is a process condition attached to the construct, not the construct itself. Adapt, and document the adaptation.
Testing the local soil.
- Dig from the subsoil, below the organic top layer; sieve out stones and roots.
- Slake in water overnight, pour off excess water, spread on a board to stiffen, then wedge.
- Make at least six test tiles per class, about 10 x 3 cm, and record the wet dimensions.
- Dry slowly in shade, never in sun or wind, and re-measure to calculate shrinkage; score a line across each tile to see cracking.
- Join tests: score and slip two small pieces and check the bond when dry.
- Adjust: if the clay is too sandy and crumbles, add a little purchased ball clay or paper pulp; if it is too sticky and shrinks badly, add sand or crushed fired clay as grog.
- Fire one or two test tiles before committing 60 vessels.
Firing. This is low-fired earthenware, not kiln work. Use a shallow pit or bonfire bed: preheat the pieces near the fire to drive off residual moisture, layer with clean wood and sawdust, cover with a metal sheet, and fire slowly. Expect breakage; plan for two pieces per learner or spares, and treat breakage as data for the science link rather than failure.
Budget. P400 covers a small bag of plastic clay or grog, sandpaper and a few tools; everything else is dug, donated or made. No learner contributes.
2. How would you teach the stages of clay, bisque firing and glaze accurately when you cannot bisque-fire or glaze?
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Use their own tiles as the textbook. Learners measure, weigh, sketch and describe the same tile at four points: wet, leather-hard (cool, firm, holds a fingerprint but still carves), bone dry (pale, warm, will not deform but is brittle), and fired (colour change, ring when tapped, irreversible). The vocabulary is then attached to an object they made, not a paragraph they memorised. Add a re-wetting test on a scrap: leather-hard clay can be joined with slip; bone-dry clay cannot.
Be honest about the technology. A bonfire reaches a few hundred degrees at best; glaze vitrifies around 1000–1250 °C. Tell learners plainly that they are doing a low-temperature firing and that a glazed surface needs a kiln. Do not pretend a bonfire produces a glaze. Instead:
- Show real glazed and bisque-fired shards borrowed from the pottery 90 km away, or invite the potter to send a sample set.
- Use a short video of a kiln being loaded and fired, with a worksheet.
- Compare their fired tile with a kiln-fired shard: colour, hardness, porosity, sound.
- Link to the science curriculum: water content, chemical change on firing, irreversible reactions, insulation and slow cooling.
Exam preparation. Bisque is the first firing that hardens the ware so it can be glazed; learners should be able to define it, sequence it and explain why it precedes glazing, using their own firing as the analogy, with the temperature difference stated clearly. Practise the exam-style questions on leather-hard and glaze in the same week as the practical, so the theory is retrieved while the experience is fresh.
Portfolio. Photographs of the tile series with measurements, a labelled diagram of the stages, and a short paragraph comparing their firing with an industrial kiln. That is stronger evidence of understanding than a worksheet copied from a textbook.
3. Set out the safety and equity plan for the firing session, including what you will do about smoke and about learners who cannot be present.
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Site and conditions. Use the covered outdoor area, at least three metres from buildings, trees and the fuel store. Check wind direction and strength on the day; abandon the firing in strong wind. Clear the ground, mark a boundary and keep the class behind it. Have two buckets of water, a bucket of sand, gloves, and the science teacher's extinguisher.
Fuel and handling. Clean dry wood, sawdust and dung only - no plastics, no painted or treated timber, no accelerants such as paraffin. Learners wear cotton clothing, closed shoes, and hair tied back; long sleeves are rolled down, not up. Tongs or long-handled tools for placing pieces; nobody reaches over the fire. A slow preheat stage to avoid steam explosions from damp pots.
Supervision and permission. Two adults present throughout, one of them the teacher. Written parental information in advance, explaining the activity and the smoke. A learner medical list to hand: asthma or other respiratory conditions means a documentation or photography role upwind, not exclusion from the unit.
Smoke. Keep the fire small and hot rather than smouldering, choose a day with light wind, warn neighbouring classes, and keep the group upwind. End the burn cleanly, cover the embers, and monitor until cold - never leave a fire unattended.
Equity. All materials from the school budget; no family contribution and no learner excluded for inability to pay. Tools are shared on a rota. A learner who misses the firing still has their greenware piece, photographs of it, the test-tile data and the written comparison, so the assessment is not lost. Any learner who is absent gets a supervised catch-up slot; the standard stays the same, only the route adjusts.