Learn Dutch: Mijn zoon is jong.

No! Unlike some other European languages, the Dutch word mijn (my) never changes its spelling based on the word that follows it. Whether the noun is a de-word, a het-word, or plural, it is always mijn.

Why do we use is instead of the 'I' form of the verb?

It is tempting to think of 'I' when you see mijn, but the subject of this sentence is zoon (son). Since 'son' is a 'he' (third-person singular), the verb is is. It works just like English: we say 'my son is', not 'my son am'.

Why doesn't jong have an -e at the end?

Adjectives usually get an -e ending when they come directly before the noun (as in de jonge zoon). However, when the adjective comes after the verb (like is here), it stays in its basic dictionary form and never gets the -e ending.

How do I pronounce the vowel in mijn?

The ij is a special Dutch sound. It sounds like a blend between the English 'eye' sound and the 'ay' sound in 'play'. Make sure not to pronounce it like the short 'i' in the English word 'min'!