Hi, current research for children/babies learning and development focusses on the brain and what happens to it when children learn.
The Science museum.org.uk
has a good section to help.
Research helps us to look at the importance of sleep. The Mental health sleep report makes good reading
Calm and quiet places
Communication & language, rhythm, rhyme and song
Healthy nutritious diet
Emotional security - attachment theory, trust & confidence.
Indoor and outdoor exploration