1. Explain it simply
偶尔 (ǒu'ěr) means 'occasionally' or 'now and then'. It marks a low-frequency action.
Word order: Subject + 偶尔 + verb phrase, as in 我偶尔喝咖啡 (I occasionally drink coffee).
It often contrasts with a regular habit: 我平时喝茶，偶尔喝咖啡 (I usually drink tea, occasionally coffee).
Keep 偶尔 before the verb - do not push it to the end or wedge it between the verb and its object.
2. Show examples
我平时喝茶，偶尔喝咖啡。
Wǒ píngshí hē chá, ǒu'ěr hē kāfēi.
I usually drink tea, and occasionally drink coffee.
偶尔 contrasts with the usual habit
他偶尔迟到。
Tā ǒu'ěr chídào.
He is occasionally late.
偶尔 sits before the verb 迟到
爷爷偶尔去公园锻炼。
Yéye ǒu'ěr qù gōngyuán duànliàn.
Grandpa occasionally goes to the park to exercise.
happens now and then, not every day
3. Share a tip
Put 偶尔 before the verb - say 他偶尔迟到, not 他迟到偶尔.