What are the best coding classes in Southampton?
Southampton counted 248,922 usual residents at the 2021 Census, and 25.6% of those aged five and over were schoolchildren or full-time students, against 20.4% across England. Ordnance Survey, Great Britain's national mapping service, moved its headquarters to Southampton after a fire in 1841, and its open postcode file is the data behind the project on this page. Modern Age Coders teaches Southampton learners aged six to sixty-seven live online, in small groups of five to ten set by level or one to one, with teachers in India and times arranged in UK hours. Nothing is charged for the first lesson. Afterwards it is USD 100 a month for a group place, or USD 150 a month for lessons with a teacher to yourself.
Southampton has 5,814 postcodes in Ordnance Survey's open Code-Point file. Suppose a program has to find one of them instantly, thousands of times a second. Scanning a list takes 2,907 comparisons on average. A hash table does it in about one: a hash function turns each postcode into a bucket number, and the lookup jumps straight there. But the hash has to be good. The obvious one, adding up the character codes, turns out to produce only 61 different answers for every postcode in the city, because they are all built from the same few letters and digits. It packs 5,814 postcodes into 61 of 7,919 buckets, with 227 in the worst. A well-mixed hash spreads the same keys over 3,901 buckets, seven at most in any one. Knowing why, and how to measure it, is the lesson Southampton's postcodes teach our teenage learners.
Facts last verified 21 September 2026. Teaching is online; no Southampton branch is claimed.
Let the learner's interests lead. Each course starts with a free live lesson, and no card is needed to book.

Python for 9 to 12 year olds, where lists and dictionaries of key-value pairs, the ideas under every lookup, arrive early.
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Python from a first line to full projects, with a week on dictionaries and sets that leads straight to this project.
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Hash maps, sets, stacks and queues built and measured, with collisions handled on purpose rather than by accident.
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SQL and database design for adults, including the indexes that make lookups in large tables fast.
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 syllabusFrom the 2021 Census tables for the Southampton local authority, published by the Office for National Statistics on Nomis.
| What was counted | Southampton | England |
|---|---|---|
| Usual residents | 248,922 | Not compared |
| In households | 238,765, 95.9% | Not compared |
| In communal establishments | 10,157, 4.1% | Not compared |
| Aged 15 to 19 | 16,752, 6.7% | 5.7% |
| Aged 20 to 24 | 26,139, 10.5% | 6.0% |
| Aged 25 to 29 | 20,718, 8.3% | 6.6% |
| Schoolchildren and full-time students, of 235,126 aged five and over | 60,197, 25.6% | 20.4% |
Residents aged 20 to 24 made up 10.5% of Southampton, and those aged 25 to 29 another 8.3%, against 6.0% and 6.6% in England.
Schoolchildren and full-time students together were 25.6% of residents aged five and over in 2021, with England at 20.4%.
Some 95.9% of residents lived in households; the other 4.1%, in communal establishments, include people in student halls.
In practice that means learners at every stage. A Southampton learner might be a nine-year-old in Bassett writing a first Python program, a Year 13 student in Sholing finishing A level Computer Science, or someone in their twenties in Ocean Village learning SQL for work, and each joins a group of five to ten at the same level.
From Ordnance Survey's own account of its history and its about page.
Ordnance Survey says this date is officially recognised as its birth, when the Board of Ordnance bought a new Ramsden theodolite to carry William Roy's triangulation forward.
A fire at Ordnance Survey's cramped Tower of London offices prompted a move to a new Southampton headquarters, in an empty former barrack building.
In the Second World War the Southampton headquarters was bombed and badly damaged, and by 1945 Ordnance Survey had produced 342 million maps for the war effort.
Today Ordnance Survey describes itself as Great Britain's national mapping service. Its head office, Explorer House on Adanac Drive in Nursling, carries a Southampton postal address; its own postcode file places that postcode, SO16 0AS, just over the city boundary in Test Valley. We have no connection with Ordnance Survey. We tell its story because the dataset on this page is one of its open products, published by a mapmaker with nearly two centuries of history in and around the city.
The file we used
Code-Point Open, dataset version 2026.3.0, gives a grid reference and district code for every postcode unit in Great Britain. Its SO file lists 18,624 postcodes, of which 5,814 fall in Southampton itself, spread across six outward codes from SO14 to SO19.
A hash table turns a key, such as a postcode, into a bucket number, so a lookup can jump straight to the right place. We stored every Southampton postcode in 7,919 buckets with two different hash functions.
| Method | Buckets used | Longest chain | Comparisons per lookup |
|---|---|---|---|
| Plain list, no hashing | Not applicable | Not applicable | 2,907.5 on average |
| Hash that adds up character codes | 61 | 227 | 75.6 on average |
| FNV-1a hash | 3,901 | 7 | 1.45 on average |
Pick a prime number of buckets a little above the number of keys: 7,919 for 5,814 postcodes, a load of about 0.73 keys per bucket.
A hash function turns SO17 1BJ into a bucket number. Keys landing in the same bucket are kept in a short list, a chain, and checked one by one.
Count how many buckets each hash actually uses and how long the longest chain grows. That, not how neat the code looks, decides the speed.
Every Southampton postcode is built from the same small set of characters, so the sum of their character codes only runs from 473 to 536: just 61 possible values. The simple hash therefore crams 5,814 postcodes into 61 buckets, 227 in the worst. It also sends anagrams to the same place every time, and there are 1,417 groups of Southampton postcodes that are rearrangements of each other, such as SO14 0AE and SO14 0EA. FNV-1a mixes every character into the whole result and spreads the same keys over 3,901 buckets.
Even a good hash collides sooner than intuition suggests. With 7,919 buckets, theory says a shared bucket becomes more likely than not after about 105 keys; drawing random Southampton postcodes 20,000 times, the first shared bucket came after a median of 96. FNV-1a also used slightly fewer buckets than a perfectly random hash would, 3,901 against an expected 4,119, a reminder that real hash functions are good rather than perfect on keys as alike as postcodes.
Learned on postcodes, used afterwards on usernames, product codes, caches, databases and the dictionary inside almost every program.
| Habit | What it looks like | What it prevents |
|---|---|---|
| Know your keys | Look at what the keys have in common before choosing a hash; postcodes reuse a tiny alphabet | A hash that ignores the structure of its keys |
| Mix every character | Use a hash in which each character changes the whole result, such as FNV-1a | Anagrams and near-duplicates piling into one bucket |
| Size the table sensibly | Keep the load below about one key per bucket and use a prime bucket count | Chains that lengthen as the data grows |
| Measure, do not assume | Count used buckets and the longest chain on the real data | A hash that looks fine on paper and crawls in practice |
| Plan for collisions | Handle shared buckets from the start, since they arrive after roughly the square root of the bucket count | Code that breaks the first time two keys meet |
The last habit is the birthday paradox at work. In a room of 23 people, two share a birthday more often than not, and a table of 7,919 buckets sees its first collision after around a hundred keys. Every hash table in every programming language is built to handle that calmly, which is why learners write their own before trusting the built-in one.
Sorting cards into labelled boxes by their first letter, then noticing which box overflows and inventing a fairer rule.
The Code-Point file read in Python, two hash functions written and measured, chains counted and the birthday paradox tested.
Indexes, caches and lookups at work, with key structure and load factor checked before performance is promised.
We are not connected with Ordnance Survey or the Office for National Statistics. Code-Point Open is published as open data; the tables, hashes and counts are our own work.
Use the ages as a rough guide; the free lesson settles the level.
Filing cards by a simple rule, spotting when one box fills up, and finding a fairer way to share them.
Mental Maths for KidsProblem Solving and Computational Thinking for KidsCharacters as numbers, dictionaries that find things by name, and a first home-made hash.
Python and AI for KidsMaths Through CodingHash functions compared on real keys, chaining and load factor measured, and collisions predicted.
Problem Solving for TeensPython for TeensIndexes, caching and hashing in databases and services, with performance measured on real data.
Data Structures & Algorithms CourseMySQL CourseBecause the gap between one step and seventy-six is invisible until someone measures it.
Ask an AI tool to write a postcode lookup and it will usually reach for a built-in dictionary, which is the right choice. Ask it to design its own hash, though, and a plausible function that adds up the characters would pass a quick test and then crawl on real data, using 61 buckets out of 7,919. A learner who has measured the chains can catch that in a code review; one who has not will ship it.
Hashing also sits at the heart of modern computing and AI. Databases index records with it, websites cache pages with it, and large AI projects use it to find near-duplicate documents in their training data. One small table of postcodes opens the door to all of those ideas.
So a Southampton teenager should still learn to program in 2026, in the city Ordnance Survey moved to in 1841: software now writes code on request, and knowing which code is quietly slow is exactly what programming teaches. The longer argument is in is learning to code still worth it in 2026.
Whichever side of the Itchen a learner lives on, a live online lesson needs no bridge.
A learner in Woolston and another in Freemantle can share one lesson without either crossing the river.
Reception, the four Key Stages, Year 9 options, GCSEs and A levels, called what Southampton schools call them, and taught in English.
The free lesson teaches something real and ends with a recommended level, course and regular weekly time, with no card requested.
Five to ten learners at one stage, from Southampton, the rest of the UK and abroad, so every level has a slot that works.
The same two times each week, about eight lessons a month, with holiday and exam pauses agreed with the teacher ahead of time.
Our teachers work on India Standard Time, which stays fixed all year, so they are four and a half hours ahead of Southampton in summer and five and a half in winter; after-school and evening lessons sit inside their day.
Across Hampshire too
Families in Eastleigh, Totton or the New Forest join exactly the same groups, because every lesson is online and groups are formed by level rather than postcode.
A free first lesson, then one of two prices.
A complete lesson with nothing to pay, closing with a level, a course suggestion and a weekly time.
Around eight live lessons a month, in a group of five to ten learners at one level.
Around eight live lessons a month, with the teacher working only with your learner.
All families outside India pay a single US dollar fee, so Highfield and Harefield pay exactly the same, and we list no prices in pounds. Billing starts only after the free lesson has fixed a course and a time; the pricing page explains pauses, missed lessons and changing between group and private teaching.
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We pick the first task by level: sorting cards into boxes for a young child, a first Python dictionary for a middle-schooler, or the Code-Point file and two hash functions for a teenager ready for real data.
What Southampton families ask us most.
The 2021 Census counted 248,922 usual residents in the Southampton local authority: 238,765 in households and 10,157, or 4.1%, in communal establishments.
In 2021, 60,197 of the 235,126 residents aged five and over were schoolchildren or full-time students, 25.6% against 20.4% in England.
Ordnance Survey says a fire at its Tower of London offices in 1841 prompted a move to a new Southampton headquarters. Its head office today, Explorer House, has a Southampton postal address. We are not connected with Ordnance Survey.
A way of storing data so that a key, such as a postcode, is turned by a hash function into a bucket number, letting a program find it in about one step instead of searching a whole list.
Because Southampton postcodes share so few characters that the sums take only 61 different values, so 5,814 postcodes crowd into 61 buckets, and anagrams such as SO14 0AE and SO14 0EA always collide.
Ordnance Survey's Code-Point Open, version 2026.3.0, lists 5,814 postcodes in the Southampton local authority, across the outward codes SO14 to SO19.
Weekday afternoons and evenings or weekends, at a UK time agreed during the free lesson. Our teachers are four and a half hours ahead of Southampton in summer and five and a half in winter.
No. We have no Southampton centre and no premises anywhere in the UK; every lesson runs live online. Learners need a computer with sound and a steady connection, and our phone number is based in India.
The first lesson is free. After that a group place is USD 100 a month for two live lessons a week, about eight a month, with five to ten learners, and one-to-one lessons on the same schedule are USD 150 a month. Course, format and time are agreed before anything is charged.
By ability, pace and aims rather than age or postcode, with five to ten learners at one level. If no group meets at a suitable time, we offer one-to-one lessons.
To the west, the Bristol page splits its city into library catchments with a Voronoi diagram, and to the north Oxford builds a Markov chain from two centuries of rain. London has a guide of its own. The England guide explains the school stages, and every UK page is linked from the UK coding page.