These groups of cells are called tissues. An organ is a group of tissues that work together to do a job. Body organs are made of several kinds of tissue. A group of organs work together to form a system. Most living things are called organisms.
Organism sounds like the word organ.
An organism is a living thing. Many organisms have organs and systems. We will examine how organisms begin to interact with their environment. Each living thing or organism has been classified into a genus and species. The genus and species are the two smallest divisions of living things.