9National Research Council (NRC).Adding it up:Helping children learn mathematics [A].In:Kilpatrick J,Swafford J,Findell B.Mathematics learning Study Committee,Center for education,Division of Behavioral and Social Sciences and Education [C].Washington,DC:National Academy Press,2001.
10Carpenter T,Lehrer R.Teaching and learning mathematics with understanding [A].In:Fennema E,Romberg T.Mathematics Classroom that Promote Understanding [C].Mahwah,NJ:Lawrence Erlbaum Association,1999.
