Print a blackboard newspaper with chalk or gouache.

Depending on where you go out, if you use chalk indoors, it is easy to modify or erase. If the blackboard can be dismantled outdoors, use gouache paint. First, rich colors and bright colors. Second, it is more weatherproof than chalk. One of the most important things is whether you have so much time to do it. Use chalk when you have less time, and gouache when you have enough time.