Why didn't you use the bloody spellchecker?

I did not think this would ever make a good topic for an article (after all, there are dictionaries and spellcheckers). However, testing my students on spelling has shown me that this can be a nice way to wrap up a lesson. Not everybody uses spellcheckers in every situation, anyway. A quick email, a short memo, a side note, or simply lack of time may be situations where people cannot be bothered. So there are certainly times when we simply write and spell the way we are used to. Even if used, spellcheckers do not guarantee complete coverage as they will not highlight similar words that exist, or recognize verb/noun structures.

The lessons learned came as a surpise even to my C1+ learners. Their issues can be broken down into four categories:

1. double letters. The question here is: how many consonants and how many vowels? You can hardly guess that from the way a word is pronounced.
2. making the right choices between a, e, i, o + u
3. silent letters
4. special cases relating to my students' mother tongue that inevitably takes takes its toll not only with regards to false friends, word order and grammar, but also in terms of spelling

Here are some examples:

1. accommodate, assessment + successful fall into the first category. How many c/l/m/s? I’ve seen many variations. It is not obvious that occasion contains a single "s", whereas in occurrence we double the "r". In lo(o)se, we shift from verb to adjective. And what happens when we put full + fill, will + full, skill + full (4x "l") together: do we end up with 4/3/2 "l"? I’d say 2, but in US English it’s 3. HANG ON…where is the double "l" then, in the middle or at the end? It depends: willful, skillful – but: fulfill. Argh.
2. a prime example for the second category is the "a-free" independent. I often see an "a" in there somewhere. Also confusing: dependant comes with an "a" when used as a noun, and even as an adjective in US English. The "e" in judge disappears in judgment in a legal context (eg a court decision). In UK English, judgement is fine in a non-legal context (judging a person/situation, or having good/sound judgement).
3. Silence is golden. Not so with spelling. The "c" in acquire/acquisition is often forgotten, as is the "n" in column, or the "ue" in colleague.
4. As my students‘ first language is German, I can draw on specific issues with address (only one d in German), committee (single m, single t, double e), and privilege, which is basically the same when it comes to i, e + the single l (save for the last e, true to its Latin origin privilegium), but causes trouble because the way it is pronounced makes some people think there should be a "d" (priviledge).

There are also combined categories presenting multiple issues: guarantee, for instance, poses vowel, double + silent letter problems.

Here is my collection of 25 words (out of several hundreds) and their neuralgic parts:

Once again: spellcheckers won't save you when words actually exist. Maybe you meant moot (not mute), imminent (not eminent), ensure (not insure), then (not than), further (not farther). In context:

In principal, this should not effect the outcome. ←nope

In principle, this should not affect the outcome. ←yes

Compare: she conducts researches?she researches the dark side. "Researches" does exist, but not as a noun (uncountable).

In my articles, I usually offer a look at my world, which is full of legal and tax professionals. For them, guarantee, judgment and threshold are horrible, but conscientious, entrepreneur and interlocutory can also give them a headache. I even saw "lu" and "loo" (as in "in lieu of").

Misspellings occur. Often, the result is just wrong. Sometimes the result is another word, another meaning, or another category (eg verb→noun). Spellcheckers and AI will not always do your homework.