In an era of social media, and amid the coronavirus pandemic, teachers' curation of instructional resources stands as an opportunity to observe teachers' planning and conceptualization of their practice in real time. This work explores the resources teachers curate, their rigor, and the effects on students' learning across years. Merging big data from Pinterest, a prominent social media platform, and administrative data from the Indiana Department of Education on 10,383 fourth- through sixth-grade students across 2010-2017, this study employed three-level hierarchical linear models to identify relationships between the inherent cognitive rigor in teachers' curated instructional tasks and students' achievement. Results indicate teachers curating resources focused on basic memorization and remembering negatively affected students' learning, whereas higher-level tasks focused on understanding and applying had a positive impact on achievement. Identified effects were comparable to those related to student and teacher attributes, signaling the importance of teachers' curation.