Definition: A scale drawing is a drawing of a real or imagined object that has been reduced or enlarged to fit on a particular sized paper. This is represented by using a scale. A scale is indicated as a ratio. For example, a ratio of 1:100. Therefore, scale drawings are drawings used to demonstrate the equivalency of dimensions.
How to Read Scales or Ratios?
An object that has a scale or ratio of 1:100 means that in the real world, a 100 unit object will be represented as 1 unit on paper. So whenever you see a ratio or scale you want to read it from left to right. Again, the first number is what is drawn on paper, the colon is read as “to” and the final number is the real world measurement.
What does the following ratio mean?
Yes, this means that 1 unit on paper is equivalent to 10 units in the real world.
How are Scale Drawings Used?
People use scales on a regular basis without even noticing it. For example, we cannot see microorganisms with the naked eye, therefore, we use microscopes. Microscopes allow us to see things that are very small by making them appear larger through a process called magnification. On the other hand, for example, when builders are going to build buildings they cannot draw the buildings the same size on paper, it will not fit. Therefore, scale drawings are used as a way to represent the actual measurements of objects whether they are big or small.
What do you think a scale with a ratio of one to one (1:1) mean? It means that the object that is drawn is the same size as the object in real life.
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MCC7.G.1 Solve problems involving scale drawings of geometric figures, including computing actual lengths and areas from a scale drawing and reproducing a scale drawing at a different scale.
MCC7.RP.2 Recognize and represent proportional relationships between quantities.
MCC7.RP.3 Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.