Wallwisher changed their name to Padlet, and in the process added some new features such as customizable backgrounds. Padlet is an engaging, effective way to share ideas being discussed in your class and is very user-friendly. You can post a question that is an extension of the lesson that day and have students respond for homework. What I love about this type of formative assessment is that it provides "wait time" for students by letting them process what they learned (or didn't learn) in class. Also, struggling students can see other student responses, which puts the content in a language they might better understand.
Below is a Padlet I created in about 15 minutes. I customized the background by uploading one of my own digital backgrounds for fun. Another amazing feature is the mobilize option that allows you to create your own QR Code. You would copy the link and input it into a free QR Code generator. Depending on the age of your students and their access to mobile devices, you can have them scan the QR Code which will direct them to their homework for the night. Another idea for those teaching in a 1:1 environment would be to display a QR Code that leads students to a warm-up question on Padlet. Boring? I think not!!!