This article describes the [corpus-name] corpus developed as part of the [project-name] project. To the best of our knowledge, this is one of the largest collections of children’s conversational speech that is freely available for non-commercial use under the creative commons license (CC BY-NC-SA 4.0). It comprises approximately 400 hours of speech, spanning some 230K utterances spread across about 10,500 virtual tutor sessions. Roughly 1,300 third, fourth and fifth grade students contributed to this corpus. The current release contains roughly 100K transcribed utterances. It is our hope that the corpus can be used to improve automatic speech recognition models and algorithms. We report the word error rate achieved on the test set using a model trained on the training and development portion of the corpus. The git repository of the corpus contains the complete training and evaluation setup in order to facilitate a fair and consistent evaluation. It is our hope that this corpus will contribute to the creation and evaluation of conversational AI agents having a better understanding of children’s speech, potentially opening doors to novel, effective, learning and therapeutic interventions.