Militant sister.

These days, I've made it a routine to teach my 6-year-old brother bits of Mandarin every day. Sweet kid, but he can get a bit restless, and he likes watching tv/playing games too much. And he reads his things so slowly my mum would often quip that one can really fall asleep while teaching him. I just say he moves at a non-human pace altogether when he's reading. Like how slow lorises move at a completely different pace when compared to humans.

I used to do the nice, kindly sister thing when I'm teaching him, but I've recently adopted the militant, angry sister stance.
I'd use a timer and threaten him with something if he doesn't finish reading/learning by a certain time. I'd fling some small objects around (seemingly) in anger where appropriate. A bit of table-banging and yelling. Exposing him to the good ole' Chinese-style education, in short. (If you think that sounds cruel, you've never been to a Chinese school)
And that works quite well actually. The brother isn't too terrified (because I'm just a sister, not his mum. If you understand familial hierarchy/ever had siblings, you'll get what I mean), and he's learning by leaps and bounds. I think he quite likes the excitement implicit in such a routine. And he sure loves the timer.
Plus, today, he got nuggets (that I fried!) after reading. If that isn't reward enough, I don't know what is.