Slide 5 is currently “Explain your thinking.” Not really any way to check that without exhaustively matching their string. Virtually impossible for such an open-ended question. Otherwise, I assume you mean what is now Slide 6. I use the following in an input’s CL as a pretty standard input check (without using a separate note for feedback), but you could modify it for a note if you really wanted it:
suffix: when not(this.submitted) ""
when check "✅"
I do a similar cellSuffix for tables to eliminate the need for another column, although sometimes it can clutter a cell with longer answers or if evaluation isn’t disabled.