====== Spielwiese ======

  * Balanceakt: https://phet.colorado.edu/sims/html/balancing-act/latest/balancing-act_de.html
  * Elektromegnetische Induktion: https://phet.colorado.edu/sims/html/faradays-law/latest/faradays-law_de.html
  * Ohmsches Gesetz: https://phet.colorado.edu/sims/html/ohms-law/latest/ohms-law_de.html
  * Nagelbrett: https://phet.colorado.edu/sims/html/plinko-probability/latest/plinko-probability_de.html
  * Druck: https://phet.colorado.edu/sims/html/under-pressure/latest/under-pressure_de.html
  * Kräfte: https://phet.colorado.edu/sims/html/forces-and-motion-basics/latest/forces-and-motion-basics_de.html
  * Ballons: https://phet.colorado.edu/sims/html/balloons-and-static-electricity/latest/balloons-and-static-electricity_de.html
  * Geraden: https://phet.colorado.edu/sims/html/graphing-lines/latest/graphing-lines_de.html

===== Geographie =====

  * http://www.ilern.ch/geographie-stadte-flusse-gebirge/
  * http://quiz-geographie.de/