The Glow Report: Bolitho Pupils Measure December's Sparkle

December at Bolitho brings the familiar signs of the season: cards on classroom walls, rehearsals in the hall and, increasingly, strings of lights around shared spaces and family homes. This year, pupils have added another seasonal tradition to the list. Rather than simply admiring the sparkle, they have been measuring it.

The Glow Report is a pupil-led festive light audit. It asks a straightforward question: what can we learn about energy use, cost and safety from the decorations that appear at this time of year? The aim is not to discourage celebration. It is to make the evidence behind our choices visible, and to give families a practical way to enjoy December with confidence.

A seasonal question with a scientific core

Fairy lights are a useful teaching resource because they connect several areas of science at once. They involve electrical power, energy transfer, cost, materials and safety. They are also familiar enough that pupils can ask precise questions about them without needing specialist equipment beyond a plug-in energy monitor and a timer.

Working in small groups, pupils examined a range of light sets. Some were modern LED strings. Others were older sets with filament bulbs, several of which had been stored in lofts or cupboards for many years. The pupils recorded the number of bulbs, the length of the string, the stated wattage and the wattage measured by the monitor. They also noted whether the set became warm in use, and whether the cable, plug or bulb holders showed signs of wear.

The project was deliberately framed as an audit rather than a competition. The question was not which family has the brightest display, but what the measurements can tell us about responsible use.

Designing a fair test

A fair comparison matters. Pupils therefore agreed a common method before taking readings. Each set was tested under adult supervision, using the same energy monitor and the same socket. Sets were run for the same short period so that pupils could confirm a stable reading. The number of bulbs and the length of each string were recorded, because a longer string will naturally use more power than a shorter one.

Pupils also discussed the difference between stated and measured power. A label may give a maximum or an approximate value, while a monitor shows what the set actually draws. Where the two differed, pupils recorded both and treated the label as a claim to be checked rather than a fact to be accepted without question.

Brightness was observed but not used as a numerical measure. The groups noted that perceived brightness depends on colour, spacing and the surroundings, so it would not be a fair variable to compare without more controlled conditions. This was an important lesson in itself: not everything that can be described can be measured easily, and not everything that can be measured answers the question that matters most.

From watts to pennies

The central calculation is accessible to most pupils and useful for families. Electrical energy is measured in kilowatt-hours, or kWh. To estimate energy use, multiply the power in kilowatts by the time in hours. To estimate cost, multiply the energy used by the tariff in pence per kWh.

As an illustration, consider a 5 W LED string and a 40 W older filament string, each used for six hours a day for thirty days. The LED set would use about 0.9 kWh. The older set would use about 7.2 kWh. At a representative domestic tariff of 24p per kWh, the estimates would be approximately 22p and £1.73 respectively. Actual costs will vary with the tariff and the time of use, but the method is the same.

The point is not the exact figure. The point is that pupils can move from a measured wattage to a meaningful estimate, and then explain the assumptions behind it. That is a valuable scientific habit: a number without its conditions is only part of the story.

What the audit revealed

Across the sets tested, LED strings consistently drew less power than older filament sets of similar length. Many also ran cooler, which pupils rightly linked to safety as well as efficiency. The audit did not conclude that every older set is dangerous, nor that every modern set is automatically suitable. It showed that age alone is not a reliable guide, and that inspection matters.

Several sets were set aside during the checks because of damaged insulation, loose bulb holders or missing instructions. Pupils also noted that timers and the simple habit of switching lights off at bedtime can reduce energy use as much as changing a bulb type. The most useful outcome was a short checklist that families can apply at home without special equipment.

A family checklist for December

• Inspect the plug, cable and bulb holders for cuts, exposed wires, scorch marks or loose parts. If a set is damaged, do not use it.
• Check that the set is intended for UK use and carries the appropriate marking. Follow the manufacturer's instructions.
• Keep lights away from water and never handle them with wet hands. Outdoor sets should be suitable for outdoor use.
• Use an RCD-protected socket for outdoor lights and avoid overloading extension leads or adapters.
• Do not run cables under rugs, through doorways or where they can be tripped over.
• Switch off festive lights before bed and when the house is empty. A timer can help.
• Keep young children supervised around lights, cables and small bulbs.
• Replace damaged sets rather than attempting repairs unless you are competent to do so.

From sparkle to scientific habit

The Glow Report will be shared with families through the school community, and pupils are preparing a short display of their measurements and safety findings. The project sits naturally within the school's wider work on energy and evidence, and it offers a simple message for December 2026: celebration and careful use can go together.

For families, the invitation is to treat the festive season as a small field study. Choose a set, check it safely, note its wattage and estimate its cost. The result may be a few pence or a few pounds, but the habit is more valuable than the number. It is the habit of looking closely, asking a fair question and using evidence to inform a choice.