Add notes about thinking routines

doc/development/open-questions/index.mdwn

@@ -111,3 +111,8 @@ Discussion of metacognitive strategies that could have computer aides.
             + https://www.mrc-bsu.cam.ac.uk/software/bugs/
             + https://www.quora.com/Are-there-any-tools-that-will-take-a-graphical-model-specified-in-the-BUGS-language-and-output-a-visualization-of-that-graphical-model?share=1
             + https://cran.r-project.org/web/views/gR.html
+- Thinking routines
+    * <https://www.theconsortiumforpubliceducation.org/resource/project-based-learning-resources-pbl/research/>
+    * <http://www.pz.harvard.edu/thinking-routines>
+    * <https://www.sadlier.com/school/ela-blog/think-puzzle-explore-visible-thinking-routine-a-professional-development-series>
+    * <https://thinkingpathwayz.weebly.com/thinkingroutines.html>