0 months
Turns head side to side in prone
Upright-bobs head but stays erect
Supine-kicks feet alternately
Upright-bears small fraction of weight on feet
Props on extended arms
Rolls to supine from prone

6 months
Sits with trunk erect in a chair
Reaches in prone
Assumes quadruped in prone
Sits unsupported for 30 seconds
Rolls to prone from supine
Crawls

12 months
Walks by him/herself
Creeps up stairs
Throws a ball with some cast
Squats to play
Walks backwards
Runs stiffly
Climbs into an adult-sized chair
Walks down stairs with hand-held assistance

24 months
Walks up an down stairs non-reciprocally
Steps onto a balance beam
Kicks a ball
Jumps down from a low step with feet together
Walks on tiptoes
Rotates when coming to stand from a supine position

36 months
Stand on one foot without support for 3-5-seconds
Jumps off the floor with both feet without support
Walks up stairs with alternating feet
Jumps forward with feet together
Rides a tricycle
Catches a large ball with arms extended
Walks on tip toes greater than 8 feet

48 months
Stands on one foot for 3-6 seconds
Throws a ball with good aim 5-10 feet
Gallops
Completes a somersault
Catches a tennis ball with two hands from 5 feet

60 months
Walks down stairs with alternating feet
Hops on one foot
Stands on one foot for 8 seconds
Skips with alternating feet
Walks forward on a balance beam without falling off >6 steps
Kicks a ball into the air