This example using RShiny shows how to add polygons to a map from a geoJSON file to show school catchment areas. The school locations are then plotted.
The geoJSON file used in this project can be found at:
https://spatialdata-accabdn.opendata.arcgis.com/datasets/c8e7887f4519434b8564a608754002cb_5/about
The coordinates for the schools can be found in the spreadsheet below.