http://plp.eleducation.org/tiering

http://eleducation.org/resources/el-dimensions-of-student-achievement-in-el-schools​

http://eleducation.org/resources/group-work-and-group-discussions 

​http://eleducation.org/resources/terrain-of-differentiation

​http://eleducation.org/resources/characteristics-of-primary-learners

​http://eleducation.org/resources/building-a-culture-of-grappling 
​https://static1.squarespace.com/static/536cd8dee4b02a974e697f0b/t/56685d9469492e802518a1da/1449680276332/ELED-ContinuumOf+Interventions-1215.pdf

​https://www.edutopia.org/blog/pbl-pilot-navigating-group-work-matt-weyers-jen-dole

https://gingerlewman.wordpress.com/2012/09/27/7-reasons-to-use-contracts-in-a-pbl-classroom-tips-for-use/

http://www.p21.org/news-events/p21blog/1840-supporting-communication-and-collaboration-in-project-based-learning-activities

https://www.edutopia.org/blog/differentiated-instruction-strategies-pbl-andrew-miller