Final answer:
Nightmares and sleepwalking are common sleep problems in children aged 3-6, while riding a bike and jumping on one foot are common motor achievements.
Step-by-step explanation:
The sleep problems common in children aged 3-6 include nightmares and sleepwalking. Nightmares are vivid and disturbing dreams that can cause fear and result in difficulty falling back asleep. Sleepwalking is when a child gets out of bed and walks or performs other activities while still asleep.
The motor achievements commonly seen in children aged 3-6 include riding a bike and jumping on one foot. Riding a bike requires balance and coordination, while jumping on one foot requires strength and motor control.