Learn Finnish: Tämä oppilas on iloinen.

Finnish does not have articles like 'a' or 'the'. The word tämä (this) does all the work of pointing out exactly which pupil we are talking about.

What is the difference between tämä and se?

Tämä means 'this' (a person or thing close to the speaker), while se usually means 'it' or 'that' (something further away or already mentioned). Since we are talking about a specific pupil right here in front of us, we use tämä.

I notice iloinen ends in -nen. Is this a common pattern?

Yes! The -nen ending is extremely common for Finnish adjectives, like iloinen (happy) or sininen (blue). In this sentence, the word is in its basic dictionary form, but keep in mind that -nen words change their stem to -se- before you add endings like the -ssa/-ssä (in) that you are learning in this lesson.

How would the sentence change if I wanted to say 'This is a happy pupil'?

You would say Tämä on iloinen oppilas. Just like in English, the adjective iloinen (happy) comes directly before the noun oppilas (pupil) when describing it.