Learn German with Felix und Franzi, click on the link https://www.goethe.de/ins/gb/en/m/spr/unt/kum/dfk/dff/ma1.html
and then chapter 4 - The Painting and watch the video about colours.
Felix und Franzi are painting so why not try learning the names of some colours!
You could design your own lockdown flag (which could include a rainbow) OR draw a picture of your choice and then label the colours in German.