▁including ▁a ▁content ▁expert ▁( s cient ist ), ▁a ▁teacher , ▁an ▁educational ▁research er , ▁and ▁a ▁professional ▁software ▁developer . ▁The ▁design ▁begins ▁with ▁ident ifying ▁specific ▁learning ▁goals ▁that ▁have ▁proven ▁to ▁be ▁concept ually ▁difficult ▁based ▁on ▁teachers ' ▁experiences ▁in ▁the ▁class room . ▁The ▁simulation ▁design , ▁look ▁and ▁feel ▁is ▁story board ed , ▁discussed , ▁and ▁then ▁finally ▁" coded ." ▁Each ▁simulation ▁is ▁user ▁tested ▁through ▁inter views ▁with ▁students ▁and ▁in ▁class rooms , ▁re - work ed ▁as ▁needed ▁and ▁re - test ed , ▁before ▁released ▁on ▁the ▁Ph ET ▁website . ▁ ▁Al ong ▁with ▁testing ▁every ▁simulation , ▁the ▁Ph ET ▁team ▁performs ▁education ▁research ▁on ▁their ▁simulations . ▁They ▁have ▁shown ▁in ▁their ▁research ▁that ▁when ▁students ▁explore ▁simulations ▁in ▁addition ▁to ▁traditional ▁l abs , ▁student ▁concept ▁understanding ▁impro ves . ▁ ▁Ph ET ▁usage ▁by ▁educ ators ▁While ▁Ph ET ▁Inter active ▁Sim ulations ▁develop s ▁the ▁simulations , ▁it ▁is ▁primarily ▁teachers ▁and ▁publish ers ▁who ▁develop ▁the ▁educational ▁activities ▁which ▁use ▁the ▁simulations , ▁sharing ▁these ▁with ▁the ▁community . ▁Cont rib utors ▁on ▁the ▁Ph ET ▁site ▁follow ▁Open ▁Education ▁Pract ices ▁( O EP ), ▁en abling ▁teachers ▁to ▁use ▁or ▁adapt ▁the ▁activities ▁freely . ▁ ▁Other ▁Open ▁Education ▁Resource ▁organizations ▁that ▁provide ▁ideas ▁and ▁reviews ▁include : ▁ ▁National ▁Science ▁Digital ▁Library ▁( NS DL ) ▁provides ▁interactive ▁Science ▁Liter acy ▁Maps ▁ ▁aligned ▁to ▁American ▁Association ▁for ▁the