In my first class, I gave students two brushes.
One is a large sheep hair, reletively soft (but harder than the sable hair in water colour painting.) In the picture is a white hair one.
The other one is a medium wolf hair. It has a beautiful bouncing strength. When you press down the brush, it reflects your strength and bounce back. I use it for thin bamboo stick, orchid flower or a freehand outline. You find in this picture the brown hair. My kids (4 and 7 years old), find it fascinating that mom dares to use the hair of the "big grey wolf".