Teachers routinely locate and use ready-made lesson plans. Reviewers evaluated more than 300 resources from three online platforms—ReadWriteThink, Share My Lesson, and Teachers Pay Teachers—for alignment to the Common Core State Standards and overall quality. Most of the materials, 64 percent, received an overall rating of very poor or mediocre. In many cases, these supplemental resources are coming from crowdsourced marketplaces, where teachers don't have access to independent reviews of the materials they're downloading.
Polikoff, N., & Dean, J. (2019). The supplemental curriculum bazaar: Is what's on line any good?  New York, NY: Fordham Institute.
https://fordhaminstitute.org/national/research/supplemental-curriculum-bazaar

Foundations for Learning Through STEM Lessons Early On

Introducing science, technology, engineering and math concepts in early grades helps establish a foundation for learning about these concepts in later grades, according to a report from the Community for Advancing Discovery Research in Education. This report draws on research and development supported by the National Science Foundation to highlight important considerations about STEM educational experiences for young children and professional learning for educators who provide those experiences. Findings show that early STEM lessons also can lead to gains in other areas, including reading and writing.

Sarama, J., Clements, D., Nielsen, N., Blanton, M., Romance, N., Hoover, M., Staudt, C., Baroody, A., McWayne, C., & McCulloch, C. (2018). Considerations for STEM education from PreK through grade 3. Waltham, MA: Education Development Center, Inc. http://cadrek12.org/sites/default/files/DRK12-Early-STEM-Learning-Brief.pdf