If you are a teacher of students in grades 3-5 in the US, you might be interested in signing up for The Pen Pal Project sponsored by the United States Postal Service and We are Teachers. Participation is free and each class receives a Pen Pal Project kit. Sign-ups end on December 12, 2021, so be sure to visit the site right away if you want to be included. Although stamps will not be part of the kit, envelopes and stationery will be provided. You can find more information here.