Submitted on: 04 May 2018.
Revised on: 22 August 2018.
Accepted on: 02 October 2018.
___________________International Journal of Science and Mathematics Education
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Submitted on: 11 November 2009.
Revised on: 10 January 2010.
Accepted on: 29 January 2010.
___________________International Journal of Science and Mathematics Education
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Submitted on: 05 June 2012.
Revised on: 02 August 2012.
Accepted on: 05 September 2012.
___________________International Journal of Science and Mathematics Education
Submitted on: 16 April 2003.
Revised on: 26 July 2003.
Accepted on: 09 September 2003.
___________________International Journal of Science and Mathematics Education
Submitted on: 25 October 2011.
Revised on: 24 January 2012.
Accepted on: 15 March 2012.
___________________International Journal of Science and Mathematics Education
Submitted on: 09 August 2001.
Revised on: 10 October 2001.
Accepted on: 26 November 2001.
___________________International Journal of Science and Mathematics Education
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