The Worksheet, in the word’s original impying, is a scrap of stationery on which 1 performs work. They come in several kind shapes, most ussually linked with junior school activity task, tax forms, or accounting or other business environments. Software is increasingly expropriating the paper-based worksheet.
It can be a printed page that a children completes with a writing instrument. No materials are required. It’s “a sheet of paper on which work schedules, working time, specific instructions, etc. are wrote. A scrap of paper on which issues, ideas, or the like, are set down in temporary form.” In school, a worksheet may have questions for students and where to write answers.
In department of accounting, a worksheet is, or was, a piece of regulated paper with rows and columns on which an accountant could log information or do calculations. These are oft called columnar pads, also typically green-tinted.
In IT, spreadsheet application presents, on a PC monitor, a UI that such one or more paper accounting worksheets. MS Excel, a popular spreadsheet application, refers to a single spreadsheet (more technically, a 2-dimensional matrix or array) as a worksheet, and it refers to a group of worksheets as a workbook.