Child care programs provide an environment for children to develop their social and emotional skills. To provide additional support for teachers in nurturing this development, we created MindfulNest, a technology tool designed to support 3 to 5 year olds’ development of emotion regulation strategies. We evaluated MindfulNest through a year-long test. We found that students of all ages did not associate particular emotion regulation skills with specific emotions. Younger students struggled to understand complex interactions and occasionally struggled to use the interface, however they were still able to use MindfulNest to regulate their emotions when guided by their teacher. Older students did not struggle to use MindfulNest or understand complex interactions and were able to successfully regulate their emotions by themselves and with teacher guidance.