Bike lock for 9 yr old?

[sntm]

Ds1 wants to ride his bike to school now. We have lots of bike thefts in our area so I want a lock that is effective but easy enough that he will actually use it. Bonus if it secures the helmet too.

[KrisM]

From a rec here: http://www.amazon.com/Master-Lock-8147D-Weight-Combination/dp/B000BD692Y/ref=sr_1_2?ie=UTF8&qid=1348275875&sr=8-2&keywords=master+lock+red+chain is what DS1 is using. It's much easier than a coil cable lock. He wears it cross-body under his backpack. His helmet goes into his locker.