This picture says it all!
Both Adventure Girl and Boy were watching as Adventure Dad left for work. They stood there next to the sliding door that leads to our patio saying "bye daddy!" over and over until they couldn't see him anymore.
I sat back at our dining table and observed as they waved goodbye. Adventure Boy is only 2 years old but he understands that dad leaves in the morning for work, but before he knows it dad is back home from work. Believe me he somehow knows the time too, when evening rolls around he starts looking out that same sliding door and begins saying: "papi?, papi?".