NSES Content Standard D  Earth and Space Science: Structure of the Earth system Grades 5-8, page 160 Soil consists of weathered rocks, decomposed organic material from dead plants, animals, and bacteria. Soils are often found in layers, with each having a different chemical composition and texture.

 
Benchmark 4C The Physical Setting: Processes that Shape the Earth
Grades 3-5, page 72
Rock is composed of different combinations of minerals. Smaller rocks come from the breakage and weathering of bedrock and larger rocks. Soil is made partly from weathered rock, partly from plant remains--and also contains many living organisms.

Benchmark 4C The Physical Setting: Processes that Shape the Earth
Grades 6-8, page 73
Although weathered rock is the basic component of soil, the composition and texture of soil and its fertility and resistance to erosion are greatly influenced by plant roots and debris, bacteria, fungi, worms, insects, rodents, and other organisms.