Post-it note with handwritten message in blue marker. The message reads: "We will not be bystanders. We will take action. All of us have a role to play. Everyone can help."

Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.

Post-it note with handwritten message in green marker. The message reads, in Hebrew, "Shalom" (Peace). Illustrated with a green heart, flanked by stars, in the lower center.

Card from a student at West Allegheny Middle School in Imperial, Pa. The front features a hand-colored illustration of a bird holding a leaf in its mouth with geometric and floral motifs. The back contains a handwritten note, as well as the stock signature: "From your friends at West Allegheny Middle School."

Card addressed to Cecil Rosenthal, written using personal details from various public sources.

Hallmark card from a member of St. Peter's Episcopal Church in Londonderry, New Hampshire. The inside reads: "Please know that you are in our thoughts and prayers. St. Peter's Episcopal Church Londonderry, NH."

Post-it note with handwritten message written in black marker. The message reads: "We are always with you. You are not alone. Be strong." A smiley face and heart appear below.

Card made by a student from the George Washington University Hillel. Front cover reads: "We Are One" with an illustrated heart below. The inside reads: "The GW community sends prayers and holds your community in our hearts. We will find a way to come out stronger."

Folded card with crayon and marker illustration. Cover features smiley face. Interior features illustration of heart and of rising sun. Text reads, "Things do get better. We are so sorry for your loss and all the pain you've endured in recent days. Sending our best wishes and love for healing and peace in the days ahead. Beth [last name redacted for privacy] of Beth Chai Congregation in Maryland.

Handwritten card from a student at Goddard Middle School in Littleton, Co. The front and back cover features the following quote: "Everyday may not be a good day BUT." The quote continues on the inside: "There is good in Every DAY!!" The card reads: "Dear Rabbi Jeffr[e]y Myers, I am very sorry to hear about the shooting that has occurred. My best wishes for you all. -7th grade student from Littleton, Colorado." The message is accompanied by a large Star of David in the upper center.

Folded card on orange paper. The front cover feature a large Star of David outlined in black marker. The inside features a cartoon of a young girl wearing a Star of David t-shirt. Creasing due to exposure to the elements at the Wilkins memorial.

Post-it note with handwritten message in green marker. The message reads: "Never again." The signature is illegible.

Post-it note with handwritten message in black marker. The message reads: "No one ever do that."

Folded card with marker illustrations. Cover reads "Best Wishes." Interior features illustration of smiling sun over water and words "Best Wishes" and name "Harper [last name redacted for privacy]."

Card from a congregant at the Holy Angels Parish. The front cover contains a stock illustration of a haloed dove flying in front of Noah's ark. Due to water exposure at the memorial site, the message in this card has been partially erased. The remaining text inside reads: "...for your loss...[f]or you...Devon from CCD Hol[y] Ange[ls]...[mem]bers of the Tree of life."

Square card with white and yellow text against blue background. Card reads, "Mitzvah4Pittsburgh. Some spread darkness. We spread light. Choose a good deed. Choose a Mitzvah. Add light to the world," followed by four options and a place for respondents to list their name and email address. Some names and email addresses have been redacted for privacy.