@article{444542,
      author = {Koba, Susan. and Mitchell, Carol T.},
      url = {http://library.usi.edu/record/444542},
      title = {Hard-to-teach science concepts a framework to support  learners, grades 3-5 / [electronic resource] :},
      publisher = {National Science Teachers Association,},
      recid = {444542},
      pages = {xvi, 256 p. :},
      address = {Arlington, Va. :},
      year = {2011},
}