A substantial body of experimental evidence demonstrates that in-person tutoring programs can have large impacts on K-12 student achievement. However, such programs typically are costly and constrained by a limited local supply of tutors. In partnership with CovEducation (CovEd), we conduct a pilot program that has potential to ease both of these concerns. We conduct an experiment where volunteer tutors from all over the country meet 1-on-1 with middle school students online during the school day. We find that the program produces consistently positive (0.07[sigma] for math and 0.04[sigma] for reading) but statistically insignificant effects on student achievement. While these estimates are notably smaller than those found in many higher-dosage in-person tutoring programs, they are from a significantly lower-cost program that was delivered within the challenging context of the COVID-19 pandemic. We provide evidence that is consistent with a dosage model of tutoring where additional hours result in larger effects. [This paper was created in partnership with the Chicago Heights school district and CovEducation (CovEd).]