Swap valuation via bond method

[ratboy]

Hello,

Something I don't get and would love someone to enlighten me please.

With Schweser to price a semi annual compounded bond they say:

coupon / 1+ (spot rate / 2)^period
coupon / 1+ (spot rate / 2)^period2
etc


Then they get to the swaps and they say to use the bond method as well. OK
But they then use the full annual coupon times 0.5, 1, 1.5 for 6,12, and 18 months
ex.

coupon / 1+ spot rate^0.5
coupon / 1+ spot rate^1
coupon / 1+ spot rate^1.5

why not divide the annual spot rate by 2 and to the power of the period as for the bond?

Thanks
Dave