Most courses and other online help including Spark's documentation is not good in helping students understand the foundational concepts. They explain what is Spark, what is RDD, what is "this" and what is "that" but students were most interested in understanding core fundamentals and more importantly answer questions like -
We are a group of Senior Hadoop Consultants who are passionate about Hadoop and Big Data technologies. We have experience across several key domains from finance and retail to social media and gaming. We have worked with Hadoop clusters ranging from 50 all the way to 1000s of nodes.