Using Screen-Capture Movies to Assess Quadrilateral Constructions in Sketchpad
Annie Fetter
Christina Foran



Part of NCTM’s Learn↔Reflect Strand
Thursday, April 14, 2011
12:30 – 1:30 pm
Session 173
Convention Center, Wabash Ballroom 1
Level: 5-9
General Session


Students’ sketches of quadrilateral constructions convey much information about the students’ understanding of quadrilateral properties and how those properties drive sound constructions. But how do you document the decisions, missteps, and self-corrections that are lost in the final sketch? Make screen-capture movies of the construction process!


Participants will

  • generate and compare properties of quadrilaterals
  • analyze Sketchpad constructions of quadrilaterals and tie construction steps to specific properties
  • view movies made by graduate students in a Sketchpad class and middle and high school students
  • see examples of the added information provided by movies over final sketches
  • hear about experiences of middle and high school teachers with quadrilateral constructions and explorations

Focus on Math:

The quadrilateral hierarchy will play a prominent role in the session, both as a feature of the movies and sketches we’ll view as well as in the participant discussion. We’ll look closely at the properties of all the quadrilaterals and discuss which of those properties are necessary and sufficient to generate a dynamic and general construction using the Geometer’s Sketchpad. Movies will illustrate student decision-making and accountable talk, both individually and in groups.