Learn Hardcore Norwegian: I morgen er det en liten konkurranse i sjakk på skolen. - Tomorrow there is a small chess competition at the school.

Both are correct and mean the same thing. Starting with I morgen just emphasizes the time a bit more, like English "Tomorrow, there is a small chess competition at school."

What does er det mean here? Is it like there is in English?

Yes. In this kind of sentence, det is a dummy subject, like English “there” in “there is/are”.

Er det en liten konkurranse… ≈ “Is there a small competition…?”
Det er en liten konkurranse… ≈ “There is a small competition…”

So:

I morgen er det en liten konkurranse…
literally: “Tomorrow is there a small competition…”
natural English: “Tomorrow there is a small competition…”

You use det + er/var/blir a lot in Norwegian to introduce the existence of something:

Det er mange elever her. – There are many students here.
Det var en gang… – Once upon a time…
Det blir fest i kveld. – There will be a party tonight.

Why is it en liten konkurranse and not just liten konkurranse?

Norwegian, like English, normally needs an article in front of a singular countable noun:

en konkurranse – a competition
konkurransen – the competition
konkurranser – competitions
konkurransene – the competitions

So you say:

en liten konkurranse – a small competition

Leaving out the article (liten konkurranse) is only possible in some very specific, mostly stylistic contexts (like headlines, lists, or fixed expressions), not in a normal neutral sentence like this.

What’s the difference between liten, lite, lita, and små?

They are all forms of the adjective liten (small/little), and they change depending on gender and number of the noun.

Indefinite singular:

en liten konkurranse – liten for masculine (and often common gender)
ei lita bok – lita for feminine (in dialects/colloquial; in Bokmål you can also just use liten)
et lite hus – lite for neuter

Indefinite plural:

små konkurranser – små for all genders in plural

Definite forms:

den lille konkurransen – the small competition
det lille huset – the small house
de små konkurransene – the small competitions

In your sentence, konkurranse is masculine, indefinite, singular: ⇒ en liten konkurranse.

Why is it i sjakk and not something like med sjakk or a single compound word?

Here, i sjakk literally means “in chess” and functions like English “a competition in chess” or “in the field of chess.”

en konkurranse i sjakk – a competition in chess

You could also make a compound:

en sjakkonkurranse / en sjakk-konkurranse – a chess competition

Both patterns are common in Norwegian:

en konkurranse i matematikk / en matematikkonkurranse
en konkurranse i sang / en sangkonkurranse

Med sjakk would sound more like “with chess” (instrumental sense), which isn’t idiomatic for this meaning.

Why is it på skolen and not i skolen?

With places like skole (school), Norwegian often uses på when talking about being at the institution, not literally inside the physical building:

på skolen – at school (as an institution / place of activity)
på jobb – at work
på universitetet – at the university

I skolen is possible but usually has a different, more abstract meaning, like “in the school system”:

Han jobber i skolen. – He works in the school system / in education.

So for “at school” as a location of an event, på skolen is the natural choice.

Could we also say Det er en liten sjakkonkurranse på skolen i morgen? Is that the same?

Yes, you can say:

Det er en liten sjakkonkurranse på skolen i morgen.

This uses a compound noun: sjakk + konkurranse → sjakkonkurranse.

The meaning is practically the same:

en liten konkurranse i sjakk – a small competition in chess
en liten sjakkonkurranse – a small chess competition

Both are idiomatic. Norwegians use compounds a lot, so sjakkonkurranse sounds very natural.

Why is the verb er in the present tense if the event is tomorrow? Shouldn’t it be future?

Norwegian often uses the present tense for future events, especially when the future is planned, scheduled, or certain.

So:

I morgen er det en liten konkurranse…
literally: “Tomorrow there is a small competition…”
meaning: “There is going to be a small competition tomorrow…”

You can also use skal:

I morgen skal det være en liten konkurranse i sjakk på skolen.
– Tomorrow there will be a small chess competition at school.

Difference in feel:

er: neutral, very common for timetables, plans, fixed events
skal være: can sound a bit more like “is going to be held / is supposed to be”, slightly more explicit future marking

Both are correct here.

Does I morgen literally mean “in the morning”? How does it also mean “tomorrow”?

I morgen is a fixed expression meaning “tomorrow.” It doesn’t mean “in the morning” in this form.

Compare:

i morgen – tomorrow
om morgenen – in the morning (as a general time of day)
i morges – this morning (earlier today)
i formiddag – late morning / before noon (today)

So your sentence is about tomorrow in general, not about the specific time of day in the morning.

What are the forms of konkurranse? Is it always masculine?

Konkurranse is a masculine noun in Bokmål (some speakers may sometimes treat it as feminine in informal speech, but masculine is standard).

Its basic forms:

en konkurranse – a competition (indefinite singular)
konkurransen – the competition (definite singular)
konkurranser – competitions (indefinite plural)
konkurransene – the competitions (definite plural)

In your sentence, you have:

en liten konkurranse – indefinite singular, which is the natural choice when you mention a competition for the first time and it’s not yet known or specific in the context.