The first layer is the crust, a skin of rock covering the planet. The core that Lehman had found was the Earth's inner core. The core that Richard Oldem had discovered turned out to be the Earth's outer core.
An operational definition is used to define the terms of a process which is needed to determine the nature of an item such or its properties such as quantity, chemical composition, etc.
The degree of operationalization vary.
Operational definitions can be defined as labels and concepts in the way they are measured.
For example: The operational definition of weight can be like this:
How many pennies are needed to balance the weight of something.
When we hang something from a spring, how much a spring streches.
