Online coding classes in Europe, taught in English

For most families this turns out to be an advantage rather than a hurdle. A child at an international school already learns in English. A child at a local school practises English for an hour or two a week in a setting where it is useful at once. Adults usually choose English classes deliberately, because the jobs, documentation and online help they want are in English. Our mentors are based in India and teach live over video; how that fits European clocks is the subject of the next section.

from datetime import datetime, timedelta
from zoneinfo import ZoneInfo

INDIA = ZoneInfo("Asia/Kolkata")
cities = ["Europe/Lisbon", "Europe/London", "Europe/Berlin", "Europe/Helsinki"]

# a class at 17:00 local time, the Friday before and the Monday after the clocks change (our example)
for day in ["2027-03-26", "2027-03-29"]:
    for city in cities:
        local = datetime.fromisoformat(day + " 17:00").replace(tzinfo=ZoneInfo(city))
        hand = local.replace(tzinfo=None) + timedelta(hours={"Europe/Lisbon": 5.5, "Europe/London": 5.5, "Europe/Berlin": 4.5, "Europe/Helsinki": 3.5}[city])
        real = local.astimezone(INDIA)
        print(day, city.split("/")[1], "17:00 -> India", real.strftime("%H:%M"), "| winter rule by hand:", hand.strftime("%H:%M"))

On Friday 26 March 2027 the rule "add four and a half hours" works for Berlin. On Monday 29 March it is an hour wrong, and so is every other hand rule in the program, because the clocks in all four cities moved on the Sunday between. The program that converts properly asks the time-zone database instead, and the database knows the EU rule. That is the whole lesson in one sentence: store a moment once, in UTC or with its time zone attached, and convert it when you need to show it.

from datetime import datetime
from zoneinfo import ZoneInfo

berlin = ZoneInfo("Europe/Berlin")
# 02:30 on 28 March 2027 never happens in Berlin: the clocks jump from 02:00 to 03:00
ghost = datetime(2027, 3, 28, 2, 30, tzinfo=berlin)
there_and_back = ghost.astimezone(ZoneInfo("UTC")).astimezone(berlin)
print("Asked for:", ghost.strftime("%d %b %H:%M"), "| what the clock shows:", there_and_back.strftime("%d %b %H:%M %Z"))

# 02:30 on 31 October 2027 happens twice: fold=0 is the first time, fold=1 the second
for fold in (0, 1):
    t = datetime(2027, 10, 31, 2, 30, tzinfo=berlin, fold=fold)
    print("fold", fold, t.strftime("%H:%M %Z"), "= UTC", t.astimezone(ZoneInfo("UTC")).strftime("%H:%M"))

Our own programs, run with Python 3 and its zoneinfo module on 3 November 2026. The 2027 switch dates follow the EU rule: the last Sunday in March and the last Sunday in October.

Calendar apps, train timetables and payment systems all have to deal with these two nights, and bugs in them are common. Python marks the second 02:30 in October with a flag called fold, so that the program can tell the two apart. We use exactly this example with teenagers and adults because it is real, short and impossible to get right by guessing.

1. Predict. Before running Version 1, write down what India time a 17:00 Helsinki class is at on 29 March 2027.
2. Autumn. Change the dates to 29 October and 1 November 2027 and explain the result.
3. Your city. Add your own European city and check it against your phone.
4. Going further. Write a function that warns if a meeting is booked at a local time that does not exist.

Standard (winter) time, from 25 October 2026 until the EU switch on Sunday 28 March 2027; after it, every European column stays the same and India is one hour earlier. Examples only, not fixed batch times.

The free first class is booked in the time zone of your own device, so a learner in Dublin and one in Athens each see their own local times. Groups are formed from learners whose times overlap, which is easy within Europe because the whole continent sits within two hours of itself.