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GeoGebraGeoGebra Classroom

directed numbers operations guess

Drag a and b along the number line. Can you estimate the positions of , , and ? Show points to see four marked positions. Can you tell which operation gives each one? Check to see the answers. Try again with other positions of a and b. Is there always enough information for you to estimate?
Would this be useful for classroom discussion? What other questions will you ask (as a teacher / learner)?