This brief is one in a series aimed at providing K-12 education decision makers and advocates with an evidence base to ground discussions about how to best serve students during and following the novel coronavirus pandemic. Student teaching placements influence teacher effectiveness. If student teaching experiences are constrained by the pandemic, teacher candidates may lose valuable experiences and schools may lose the opportunity to shape and evaluate prospective hires. Teacher preparation programs and student teaching experiences play a major role in determining where candidates take job placements, in ways that can influence both job markets and staffing shortages. Teachers and teachers-in-training who participate in online practice teaching see significant improvements in teaching skills. School systems can provide in-service supports for new teachers whose student teaching experiences were interrupted or incomplete. Stronger partnerships between teacher preparation providers and remote districts have the potential to bring significant benefits, both for student teachers and for districts facing staffing shortages. Student teachers represent an important pool of additional talent for schools; creative deployment of student teachers could provide a major boost as the COVID-19 crisis continues. Low-quality teacher mentoring programs, as well as those that are not sustained across multiple years, are likely to be ineffective. Teacher effectiveness might show up differently in an online setting -- so relying on past measures of teacher quality will likely be insufficient.