Observation involves directly perceiving something using the five senses, while inference uses background knowledge to explain observations. Qualitative observations describe attributes, while quantitative observations provide numbers. For a wet classroom floor, possible inferences are a ceiling leak, spilled water, or janitor preparation. An old wooden pistol with a rock on the hammer can be inferred to be an early weapon that uses projectiles and hammers rocks. Sheet music from 1763-1816 that discusses dying and eternity can be inferred to be a religious song from that era.