Sauvie Island is close to where they live - and easy peasy access. Skyline school and Sheltered Nook Rd are in NW Portland, as is Sauvie.
But, for further evidence of the proximity, see this link of a house for sale on Sheltered Nook Rd. The realtor listing includes in the address description, the area of Sauvie Island.
http://www.movoto.com/or/16230-nw-sheltered-nook-rd-portland/491_10032974.htm
By the way, the house for sale, is the neighbor to the Hormans; the same house where the grandmother lives who authorized an interview by her grandson who referenced the cool electric project on Science Fair day, that Kryon was supposedly headed to before he vanished. Details on that interview are in the IB Science Expo/ Electric project WS thread from many, many days ago.
I have driven Skyline, Germantown, Kaiser, Cornelius Pass too many times to count - including Sauvie...it's all one big beautiful area in NW Portland. And all very relatively close to downtown Portland as well - straight down southbound hwy30. See my post in the locals section last week or week before on how tied together all these areas are to each other.