laugh (2 months), pedal a tricycle (2 years), sit without support (5-6 months), feel ashamed (2 years), walk unassisted (1 year), stand on one foot for 10 sec (4.5 years), recognize and smile at mom/dad (4-5 months), kick a ball forward (20-22 months), think about things that cannot be seen (2-6 years/12 years), make two word sentences (20 months)