Background: The integration of Text-to-Speech (TTS) and virtual reality (VR) technologies in K-12 education is an emerging trend. However, little is known about how students perceive these technologies and whether these technologies effectively facilitate learning. Objectives: This study aims to investigate the perception and effectiveness of TTS voices and VR agents in a K-12 classroom setting, with a focus on information recall. Methods: Using a recent TTS architecture, we developed four different synthetic voices based on 5, 10, 15 and 20 h of training materials. Two experiments were conducted involving students in a K-12 setting. The first experiment examined students' evaluations of TTS voices with varying hours of training material and the impact on information recall. The second experiment assessed the effect of pairing TTS voices with a VR agent on students' perception and recall performance. Results and Conclusions: Human voices received superior quality ratings over TTS voices within the classroom context. The integration of a VR agent was found to enhance the perception of TTS voices, aligning with existing literature on the positive impact of virtual agents on speech synthesis. However, this incorporation did not translate to improved recall, suggesting that the student focus may have been compromised by the VR agent's novelty and its design limitations.