In a baby 3 to 6 months of age

• Head falls back when picked up while lying on back
• Feels stiff
• Feels floppy
• Seems to overextend back and neck when cradled in someone’s arms
• Legs get stiff and cross or scissor when picked up

In a baby older than 6 months of age

• Doesn’t roll over in either direction
• Cannot bring hands together
• Has difficulty bringing hands to mouth
• Reaches out with only one hand while keeping the other fisted

In a baby older than 10 months of age

• Crawls in a lopsided manner, pushing off with one hand and leg while dragging the opposite hand and leg
• Scoots around on buttocks or hops on knees, but does not crawl on all fours

(Source: CDC)