Use op with a day (op maandag), in with a month (in mei), and om with a clock time (om acht uur). Days and months are written in lower case, unlike English.
Examples
- Op woensdag heb ik les.
- On Wednesday I have a class.
- In april ga ik naar Wenen.
- In April I'm going to Vienna.
- We spreken om acht uur af.
- We're meeting at eight o'clock.
The mistake to avoid
Lower case: maandag and april, never "Maandag".
Where this fits in
Numbers, days, time, Dutch A1: Count, talk about days and months, give the time, and handle numbers in real situations.