Learn Polish: Rodzice pozwalają nastolatkowi samodzielnie wybierać. - Parents allow the teenager to choose independently.

The verb pozwalać (to allow) requires the person receiving the permission to be in the Dative case. Think of it as giving permission to someone. This verb is then followed directly by the infinitive wybierać (to choose) to show what action is allowed.

Why use the imperfective verb wybierać instead of the perfective wybrać?

The sentence describes a general, ongoing parenting habit rather than a single event. Using the imperfective wybierać emphasizes the continuous or repeated nature of making choices. If they were giving permission for one specific choice right now, you would use the perfective wybrać.

The base word for teenager is nastolatek. Why isn't the Dative form nastolatekowi?

The word nastolatek has what is called a fleeting 'e'. When a suffix is added to decline the noun, that last 'e' drops out of the stem. The stem becomes nastolatk-, and adding the standard masculine Dative ending -owi results in nastolatkowi.

Could I put the adverb samodzielnie at the very end of the sentence?

Yes, Polish word order is flexible. Saying Rodzice pozwalają nastolatkowi wybierać samodzielnie is also completely natural. Placing samodzielnie before the infinitive just places a slight, natural emphasis on the fact that the choosing is done independently.