You can use one color of yarn or two colors of yarn to crochet this hat.

Size:
1 - 3 Years - Circumference of the head 18” - 19”
3 - 10 Years - Circumference of the head 19” - 20.5”
Adult Small/Medium - Circumference of the head 21” – 22”

Material and tools:

100g Any light worsted or DK weight yarn: approx. 180m - 200/100g for Main Color.
50g Any light worsted or DK weight yarn: approx. 180m - 200/100g for Contrasting Color.
Crochet size E (3.5 mm) hook, size D (3 mm) hook,

You can use multiple strands of the yarns to make up a single strand of worsted weight approx. 180m - 200/100g.