This case study explores two popular online twitter communities (#MTBOS and #iteachmath) with a view to understanding the opportunities that they offer for teacher professional learning. Topic modelling was used to analyze tweets with the harshtags #MTBOS and #iteachmath, each representing tweets from both online communities, to understand opportunities and resources for teaching learning and growth. Sentiment analysis was carried out to understand teacher sentiments about both communities while N-gram analysis was employed to analyze words that occur together in both communities.