This is a 5 note scale exercise. I like to warm up with this. Once you get the hang of it, it only takes a few minutes to go through the whole thing. If you've ever learned any instrument or been in a choir, you've probably done or heard something similar to this. It's not the most fun thing in the world, but it really does help.
You can practice this all over the instrument in different scales. Depending on the range of your dulcimer, some scales (like F, or E) are not going to work with this specific pattern, even if you actually have all the notes on your instrument. It's fun to learn new ways to play those scales and I highly encourage trying it.
Try to follow the rule of not crossing your left hand over your right or vice versa. Even if you have to hit two notes in a row with one hand, it's better than tripping over yourself. Just remember, if you use one hand to hit two notes in a row, it will reverse your leading hand and you'll need to do it again in order to get thing back to normal.