What are suitable materials for very young children?

When you look online or in stores for toys for young children, many toys are offered for lots of money where they make noises, have lights, music, and other such things. None of them are necessary. Empty plastic containers, with and without lids and empty boxes are wonderful toys for exploring all sorts of learning. Comparing sizes by putting one thing in another teaches science and math without anyone instructing the child. Listening to the difference in sounds as these containers and boxes are clapped together or banged on the floor or against a table teaches difference in pitch, volume, and other musical concepts. More to come.