(Portland, OR)  --  Portland voters will be asked this spring to decide whether to approve a 790-million-dollar bond to fund construction and renovation of schools across the Portland Public Schools district.  The PPS board approved having the measure go on the May ballot.  Officials say if the bond is approved, the average owner of a home valued at 300-thousand dollars would pay 420 dollars a year for the first four years, and then about 200 dollars a year for the duration of the levy.  Projects would include renovating Benson and Madison high schools and rebuilding Lincoln High and Kellogg Middle.