1. First draw a circle along a round object, but leave a gap and draw a small triangular watermelon in the gap.

2. Draw the wavy texture of the watermelon on the circle and draw the overall shape of the watermelon.

3. Color the big watermelon with a green paintbrush spaced out on the wavy lines, paint the gap with another green color, paint the small watermelon red with black dots on it, and the watermelon sketch is complete.