What is the meaning of technology "affordances" and "constraints" in terms of education?

       The meaning of technology “affordances” is used to expresses properties of an environment which interaction with a user can enhance the learning of potential of an individual. Technology “affordances” are the ways in which technology offers or supports certain things in relation to teaching and learning. Technology used for education purposes must be based on a knowledgeable pedagogy with a strong attention to the course learning objectives, instructional strategies and assessment methods. Teachers have to be aware of the varied “affordances” of any technology that could be leveraged to support teaching and learning effectively. Some “affordances” of technology are information, automation, representation, and communication/collaboration with peers and experts. These “affordances” of technology can help the educator treat their technology for the classroom as a knowledge base related to their pedagogy.

            The meanings of technology “constraints” in terms of education are the things that limit the “affordances” and the properties of action associated with them. For example, time and access issues could be some technology "constraints" in education because the teachers have to set time aside to incorporate the technology into their lesson plan and curriculum activities to utilize technology effectively in the classroom. Another technology “constraint” is that teacher’s learning objectives must be clear and accept that the technology device could break down and fail. Also, some teachers may come across glitches in their technology being used in their classroom and can hold up the lecture. Technology can be a complex teaching tool but teachers must remain vigilant and set the appropriate tasks for students to maximize the benefits of using the technology tool.

I have included three live links in relationship to this topic:
 http://centres.smu.edu.sg/cte/innovative-development/affordance-of-technology/
 http://www.tel-thesaurus.net/wiki/index.php/Educational_affordance
 http://www.isteconference.org/2012/uploads/KEY_70232305/M_Taylor_ISTE2012_RP.pdf