I found reflecting on Culture particularly interesting. Engaging the children in environment, framework and social identities with conversations w/parents and representing culture in your environment with backgrounds, upbringings, and stories. Culture can be complex.
I also thought the portion pertaining to choosing materials simple-complex-super complex was very helpful and the example of using water for several age groups. School age children could be scientific, Preschoolers could use water for problem solving and Infants could use water for sensory play.
Framework is how we see ourselves in the world and how we see others in the world. It is important because a child could grow up not trusting. We can reflect culture with languages and images. Do not use the tourist affect or traditional. Every culture is not the same across the board.
Many quality items and toys can be purchased from a daycare going out of business, second hand store and DIY etc. Most daycares consist of blocks, dolls, cars, play dough, crayons, and dress up clothes. These are the basics and there is no need to clutter or overwhelm the children.