Permanent lines on the chalkboard

[mypugcantread]

I noticed on the Spalding website a photo that shows permanent lines on the chalkboard.
This is a great idea. How do you do it? (I have used Chalk Markers but after a week it needs to be reapplied).

Thanks

[Betty]

That's a good question. As a teacher, I used a black permanent marker and a thin strip of wood for making straight lines on the board (or a yard stick can be used). The permanent marker stays visible for most of the year on the board if you use a dark color on a green or white board. Red permanent marker works fairly well on a black board.
Betty