One of the most common uses for remote sensing vegetation indices such as NDVI is for monitoring the growth of a crop. Depending on the growth stage, different indices can be better at detecting change due to the the different spectral bands they use.
We have created the below tutorial video that explains these indices and demonstrates how they can be practically used to monitor crop growth at different stages, all in under 5 minutes.
https://youtu.be/1kcUNdyIeaM