For safety reasons. If they worked alone - and something happened to them - no-one would know there was anything wrong until it was too late to help.
curriculum work groups
They don't necessarily work in groups, they just tell a partner or something, what they thought of the experiment that he/she was working on.
public-interest groups work for the bnefits of all citizens.
Most of the work of the legislature is done in groups called committees.
Groups of cells that work together are called tissues.
Public interest groups
Groups of cells that work together are called tissues.
Groups of cells that work together are called tissues.
Groups of cells that work together are called tissues.
Groups of cells that work together are called tissues.
Groups of cells that work together are called tissues.
Groups of cells that work together are called tissues.