What are the best coding classes in St Asaph?
St Asaph and Trefnant, the middle-layer area that includes the city, had 5,301 usual residents at the 2021 census, at 165.8 people per square kilometre. Cadw's listing for the cathedral records a monastery founded by St Kentigern about 560. St Asaph learners from six to sixty-seven have live video lessons with our teachers in India, either one to one or in a class of five to ten at one level, timed around Welsh school days and working hours. There is no fee for the opening lesson; after it, a place in a class is USD 100 a month and one-to-one teaching is USD 150 a month.
Cadw describes St Asaph's cathedral as standing at the top of the hill, and the city sits in the Vale of Clwyd with high ground on both sides. Our St Asaph project asks which way those slopes face. Teenagers load Ordnance Survey's 50 metre height grid for a 30 kilometre square, 360,000 heights in all, and run the Sobel operator, a small grid of weights that image software uses to find edges, to work out how steeply and in which direction the ground falls at every point. Within 6 km of the River Clwyd, the eastern side has more than five times as many steep cells as the western side, and they face west, down into the vale.
Facts last verified 23 September 2026. Teaching is online; no St Asaph branch is claimed.
Start from whatever the learner enjoys today and pick the closest course. Each one begins with a free live lesson, booked without card details.

Block programming for younger children, from simple games to drawing a hill that shades itself as a light moves.
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Gradients, angles and grids worked out in short programs, the geometry behind every slope on a map.
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Python from first lines to full projects, enough to read an Ordnance Survey height grid and run image filters over it.
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Python for adults working with maps, photographs or scans, where edges and gradients carry the useful information.
See the syllabusBrowse the course atlas for more than one hundred options and use the coding roadmap to check prerequisites.
The four we are known for
These run underneath everything above. Every one is live and online, placed by ability rather than by age, and the first class is free.

Python, web and AI projects where the learner still owns the thinking.
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Automate the work you already do, then let AI carry part of it.
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Train a model, read what it learned, and be able to say why it is wrong.
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Run AI coding agents on real work without losing control of the codebase.
See the syllabusResults from the 2021 census, published by the Office for National Statistics through Nomis, for the middle-layer areas the House of Commons Library calls St Asaph and Trefnant, and Rhuddlan and Bodelwyddan, alongside Denbighshire and Wales.
| Area | Usual residents | Students among those aged 5 and over | Residents per square kilometre |
|---|---|---|---|
| St Asaph and Trefnant | 5,301 | 15.0% | 165.8 |
| Rhuddlan and Bodelwyddan | 6,378 | 16.9% | 210.2 |
| Denbighshire | 95,817 | 18.0% | 114.5 |
| Wales | 3,107,494 | 19.9% | 149.9 |
St Asaph and Trefnant had 175 residents in communal establishments, and 761 of its 5,087 residents aged five and over were in full-time education.
In St Asaph and Trefnant, 8.1% of residents were aged 70 to 74, against 6.9% across Denbighshire and 5.8% in Wales.
Rhuddlan and Bodelwyddan, to the north, is the more densely settled neighbour, with 210.2 residents per square kilometre.
Each percentage is taken from its own census table, since every table is adjusted separately for privacy. Our St Asaph classes bring together the city and the villages of the vale. A Pen-rhewl seven-year-old building a first game, a Year 10 student from The Roe starting WJEC GCSE Computer Science and a Tremeirchion adult learning Python to organise a photo archive might each join a different class, grouped by level.
Dates below are from Cadw's full report for the Cathedral Church of St Asaph, record 1460, listed at Grade I on 16 November 1962.
Cadw records that the monastery was founded by St Kentigern of Glasgow and continued under St Asaph, and that the see was re-established in 1143, when a Norman cathedral was built.
A central tower was added in 1391 or 1392 by Robert Fagan; about ten years later the cathedral was burnt by Owain Glyndwr, and restoration was completed under Bishop Redman in 1482.
Cadw notes that the top of the tower was blown down on that day. The full restoration came between 1867 and 1875 under Sir George Gilbert Scott.
Just north of the cathedral stands the Translator's Memorial, listed at Grade II (Cadw record 1461). Cadw describes it as a monument to Bishop William Morgan and the translation of the Bible into Welsh, commissioned in 1888 on the tercentenary and unveiled on 22 April 1892; its inscription gives the year 1588. Cadw also lists the parish church of St Kentigern and St Asaph and the Old Palace, below the cathedral, at Grade II*, and its register of historic landscapes includes the Vale of Clwyd itself. We have no connection with Cadw or the cathedral, and the history here is Cadw's.
Where the height data comes from
OS Terrain 50 is Ordnance Survey's free height model of Great Britain, one height for every 50 metre square. Its highest point in our 30 kilometre square is 554.5 metres, 70 metres from the spot Ordnance Survey's gazetteer names Moel Famau.
The Sobel operator looks at the eight neighbours of every cell, weighting the nearest ones twice as heavily, and returns how fast the height changes towards the east and towards the north. From those two numbers come the slope and the direction the ground faces.
| Distance from the river | Side | Steep cells | Average direction faced | Facing east | Facing west |
|---|---|---|---|---|---|
| 0.5 to 6 km | West of the Clwyd | 2,308 | 73 degrees (east) | 32.8% | 20.8% |
| 0.5 to 6 km | East of the Clwyd | 12,605 | 260 degrees (west) | 13.7% | 39.2% |
| 0.5 to 3 km | East of the Clwyd | 1,217 | 241 degrees (south-west) | 9.0% | 63.3% |
Before touching real data, run Sobel over a made-up tilted plane. It returns the exact gradients, 0.1 east and 0.05 north, so the code and the scaling are right.
Turn the two gradients into a slope angle and a compass direction for all 360,000 cells. Only 12.7% of the square is steeper than 10 degrees, and 1.8% steeper than 20.
Directions wrap around: the average of 350 and 10 degrees is north, not south. So average them as arrows, adding up their east and north parts, which is called a circular mean.
The two sides of the vale are not mirror images. Within 6 km of the river, the eastern side has 12,605 steep cells and an average height of 144 metres; the western side has 2,308 steep cells and averages 57 metres. The steep eastern slopes face west, into the vale, whichever distance band we use, and on the nearest band, 0.5 to 3 km, 63.3% of them face west. The gentler western side leans east, towards the river, but less decisively. Neighbouring cells on a slope are not independent evidence, so we give no p-value; the consistency across every band is the evidence.
Hillshading uses the same numbers to draw the land: pick a direction for an imaginary sun, work out how squarely each cell faces it, and shade the cell by that amount. A learner who lights the vale from the west sees the eastern hills glow and the western side fade, the same asymmetry the table describes. Checking Sobel against a simpler two-point difference gives a median disagreement of just 0.12 degrees, so the pattern is not an artefact of the method.
Learned on the Vale of Clwyd, then used for photographs, medical scans, satellite images and any grid of numbers where edges and gradients carry meaning.
| Question | For the Vale of Clwyd | What goes wrong if you skip it |
|---|---|---|
| Is the code right? | Sobel tested on a plane with known gradients | A scaling slip that makes every slope wrong |
| Which way is north? | Grid rows run north to south, so the sign is flipped | Every slope reported facing the wrong way |
| How are directions averaged? | A circular mean of arrows | North-facing slopes averaging to south |
| What counts as a side? | Bands measured from the river line | Distant hills mixed in with the valley walls |
| Are the cells independent? | No p-value; bands compared instead | A tiny p-value from thousands of look-alike cells |
The second row is the easiest to get wrong. A height grid is stored with its top row in the north, so moving down a row means moving south. Forgetting to flip that sign turns every north-facing slope into a south-facing one, and the result still looks perfectly plausible. The plane test in step one is what exposes it.
Building a hill from numbers on squared paper, then shading the squares that face a torch held to one side.
Grids, image filters, the Sobel operator and circular statistics in Python, on Ordnance Survey height data.
Edge detection and gradients for photographs, scans or maps, with the method tested before it is trusted.
We have no connection with Ordnance Survey, Cadw, St Asaph Cathedral or Denbighshire County Council. The height grid, river network and census tables are published openly; the gradients, directions and shading on this page are our own analysis.
Treat the ages as a rough guide; the free lesson shows the right starting point.
Drawing on a grid in block code and colouring squares by a simple rule.
Scratch Coding for KidsCoding for KidsRise over run, angles and small grids of numbers in Python, with a program that finds the steepest step.
Python and AI for KidsMaths Through CodingThe Sobel operator, slope, aspect, hillshading and circular means on real Ordnance Survey data.
Python for TeensAI and Machine Learning for TeensEdges, gradients and filters on photographs, scans and maps, tested against a known answer first.
Python MasterclassData Science CourseBecause the first layers of many image systems do something very like the Sobel operator, and understanding it removes the mystery.
The Sobel operator is a nine-number grid slid across an image. Convolutional networks learn thousands of grids like it, and the earliest ones often end up resembling edge detectors. A learner who has written one by hand, and run it over a real valley, has seen from the inside what those systems start with.
The sign trap is the other lesson. A flipped north would make every slope face the wrong way while the map still looked sensible. AI output can be wrong in exactly that confident, plausible way, and only a test against a known answer, like the tilted plane, catches it.
So a St Asaph teenager should keep learning to code in 2026, in a city whose cathedral tower Cadw records being blown down in 1714: machines can read images now, but someone has to check which way is up. The longer argument is in why coding is worth learning in 2026.
St Asaph is small, and many learners live in the villages across the vale and on the hills around it. Online, each of them is as near to the lesson as the cathedral.
A learner in Nant-y-Patrick and another in Waen Goleugoed can share a class without anyone crossing the Clwyd.
Our levels follow Welsh school years and the Curriculum for Wales, and we use WJEC GCSE and A level course names; lessons are taught in English.
The free lesson has the learner build something real, then the teacher recommends a level, a course and a weekly time. No card is ever asked for.
Five to ten learners at the same stage, from St Asaph, the rest of the UK and abroad, so every level has workable times.
Two fixed lessons weekly, about eight a month, with school holidays and exam weeks agreed with the teacher beforehand.
India keeps one time all year, so a 5 pm lesson in St Asaph begins at half past nine at night for our teachers in summer and half past ten in winter.
Across North Wales
Learners in Rhyl, Denbigh, Ruthin or Prestatyn join exactly the same classes, because all lessons are online and classes are grouped by level.
Your first lesson is free, then there is a single monthly fee.
A full lesson at no cost, ending with a recommended level, course and weekly time.
About eight live lessons a month in a class of five to ten learners at one stage.
About eight live lessons a month, with the teacher working with your learner alone.
Families in Tremeirchion or Cwm pay in US dollars, as all families outside India do, and pound prices never appear on our site. Billing starts only after the free lesson, once a course and a weekly time have been agreed with us; the pricing page covers pausing, missed lessons and changing between a class and one-to-one lessons.
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The first lesson matches the learner: a shading game on a grid for a young child, a short Python program that finds the steepest step in a row of heights for a beginner, or Ordnance Survey's height map and the Sobel operator for a teenager ready for image processing.
What St Asaph families ask us most.
Census 2021 counted 5,301 usual residents in St Asaph and Trefnant, the middle-layer area that includes the city, at 165.8 people per square kilometre. Denbighshire as a whole had 95,817.
Denbighshire is more thinly settled, at 114.5 residents per square kilometre against 149.9 for Wales, and 6.9% of its residents were aged 70 to 74 in 2021, against 5.8% in Wales.
A small three-by-three grid of weights slid across an image or a height map. It measures how fast values change across and down the grid, which gives the steepness and direction of every slope, or the edges in a picture.
Within 6 km of the River Clwyd, the eastern side has 12,605 cells steeper than 10 degrees and they face west on average, into the vale. The western side has 2,308 steep cells, which lean east. The valley is steeper and higher on its eastern side.
From OS Terrain 50, Ordnance Survey's free height model with one value for every 50 metre square, and the river line from OS Open Rivers. We are not connected with Ordnance Survey.
Cadw's listing report records a monastery founded by St Kentigern about 560 and a see re-established in 1143, with the building rebuilt and restored many times since, most fully between 1867 and 1875. It is listed at Grade I.
Families in St Asaph usually take an after-school slot, a weekday evening or a weekend morning, fixed in the free lesson. Our teachers in India are four and a half hours ahead of Wales in British Summer Time and five and a half hours ahead in winter.
No. We have no St Asaph centre and no premises anywhere in the UK, as every lesson is live online. Learners need a computer with sound and a steady connection, and our phone number is Indian.
The first lesson is free. After it, a group place is USD 100 a month for two live lessons a week, about eight a month, with five to ten learners; one-to-one teaching on the same timetable is USD 150 a month. Nothing is charged until the course, format and time are agreed.
By level, pace and goals rather than age or where they live, with five to ten learners at the same stage. If no group suits the learner's week, we offer one-to-one lessons.
Along the coast, the Bangor page asks whether Anglesey's sunshine changed or only the instrument measuring it, and in the south Swansea hunts for the moment roadside air changed. Learners taking WJEC GCSE Computer Science or WJEC GCSE Digital Technology have pages of their own. The Wales guide explains how our levels fit Welsh schooling, and the UK coding page leads to every other city.