Wallwisher is one of a number of online idea walls which can be used to collaborate.  You can create a wall and then email a link to your students.  They then share their ideas by creating notes.  These look like post it notes and at their most basic level include text.  You can however also link to images, video, audio and websites to expand on the ideas provided.

There are other clear uses for this tool including demonstrating work, peer
feedback, discussion around a topic, etc.

Here is a link to access wallwisher.  You don't really need a tutorial to get started with wallwisher, building and sharing a wall is easy to do, just follow the instructions on the website.  Below is an example wall.  Once you have made a wall it will be there un