I've watched a number of Hallmark movies and here are the reasons. They typically are low-stress (no explicit violence, no bad language, no scenes of immorality, happy endings). Also they generally involve talented and good-looking actors. However, what they lack is unique and well-crafted stories (quite predictable plots), much drama, and much realism.
Beyond the Blackboard fits all the above (including some engaging child acting) but reaches higher than typical. It is helped by the fact that it is based on the true story "Nobody Don't Love Nobody" by teacher and advocate Stacy Bess, the main character in the movie. Though the film tames down the realism, it still manages to shine light on the the traps of homelessness that are difficult to escape, the common needs we all share, and the impact of family. The story also encourages those who are more fortunate to sacrifice and take action, out of simple humanity and also the priceless rewards that follow having a positive impact on children's lives. Being a lifelong educator myself, I also empathize with the value the film places on a safe and accepting learning environment, especially for children who don't have that at home and naturally long for it.
I think people who may or may not be great fans of Hallmark movies will be pleasantly surprised at this one.