US Customary Measurement System Introduction to Engineering Design © 2012 Project Lead The Way, Inc.

The U S Customary System Presentation Name Course Name Unit # – Lesson #.# – Lesson Name The U S Customary System System of measurement used in the United States Similar to the British Imperial System of Measurement, but not identical Common U S Customary Units Measurement Symbol Unit length in inch ft foot mi mile mass slug force lb pound time s second thermodynamic temperature F Fahrenheit degree

Presentation Name Course Name Unit # – Lesson #.# – Lesson Name

Recording Measurements Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Recording Measurements A measurement always includes a value and unit of measurement A measurement always includes error No measurement is EXACT A measurement is the best estimate of a quantity

Precision and Accuracy Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Precision and Accuracy Precision (repeatability) = The degree to which repeated measurements show the same result Accuracy = The degree of closeness of measurements of a quantity to the actual (or accepted) value High Accuracy Low Precision Low Accuracy High Precision High Accuracy High Precision Low Accuracy Low Precision

Recording Measurements Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Recording Measurements Ideally, a measurement device is both accurate and precise

Fractional Length Measurement Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Fractional Length Measurement A typical ruler provides A 12 inch scale (ruler) in US Customary units Each inch is divided into smaller divisions, typically 1/16” increments

Recording Measurements Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Recording Measurements General Rules Digital Instruments: Record all the numbers, including zeros after the decimal point, exactly as displayed Decimal scaled Non-digital Instruments (mechanical): Record all digits that you can certainly determine from the scale markings and estimate one more digit Fractional Scaled Instruments: estimate to half of the smallest increment 1/4” scale ruler you would estimate to 1/8 of an inch 1/2” scale ruler you would estimate to 1/4 of an inch 1/16” scale you estimate to 1/32 of an inch

The Inch The divisions on the U S Customary units scale are easily identified by different sized markings. The largest markings on the scale identify the inch.

Presentation Name Course Name Unit # – Lesson #.# – Lesson Name The Inch Each subsequently shorter tick mark indicates half of the distance between next longer tick marks. For example the next smaller tick mark indicates half of an inch = ½ inch 1/2

Presentation Name Course Name Unit # – Lesson #.# – Lesson Name The Inch Half of a half = ¼ inch. An English scale shows ¼ inch and ¾ inch marks. All fractions must be reduced to lowest terms. 1/4 3/4 2/4

The Inch Half of a quarter = 1/8 inch 1/8 3/8 5/8 7/8 2/8 6/8 4/8 Presentation Name Course Name Unit # – Lesson #.# – Lesson Name The Inch Half of a quarter = 1/8 inch 1/8 3/8 5/8 7/8 2/8 6/8 4/8

The Inch Half of an eighth = 1/16 inch 1/16 5/16 9/16 13/16 3/16 7/16 Presentation Name Course Name Unit # – Lesson #.# – Lesson Name The Inch Half of an eighth = 1/16 inch 1/16 5/16 9/16 13/16 3/16 7/16 11/16 15/16 14/16 2/16 6/16 10/16 4/16 12/16 8/16

The Inch Half of a sixteenth = 1/32 inch 3/32 1/32 5/32 2/32 4/32

Measurement: Using a Fractional Scale Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Measurement: Using a Fractional Scale How long is the rectangle? Let’s look a little closer

Measurement: Using a Fractional Scale Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Measurement: Using a Fractional Scale How long is the rectangle? Inbetween in. and in. Closer to the middle than the tick marks 4/32(1/8) 6/32 (3/16) What is the midpoint of 2 1/8 and 2 3/16? 5/32  

Recording a Measurement: Using a Fractional Scale Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Recording a Measurement: Using a Fractional Scale Do you think we are certain to the nearest ten thousandth? NO We round 1/16” scale rulers to the nearest hundredth because we are only certain to the tenth and we take one more decimal place for an estimate. 2.16 in.

Recording a Measurement General Rule Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Recording a Measurement General Rule Record fraction measurements to the nearest 1/32 inch Record decimal equivalent to the nearest hundredths of an inch on We will always do this on 1/16th increment rulers. 2 5 32 in.

Record the measurement in fraction and decimal Presentation Name Course Name Unit # – Lesson #.# – Lesson Name Record the measurement in fraction and decimal 1. Record fraction 2. Convert fraction to decimal Blue = Red =

Stop Complete problem 1 -5 in activity

What is the length of the blue and red rectangle Presentation Name Course Name Unit # – Lesson #.# – Lesson Name What is the length of the blue and red rectangle 1. 2. 3. Blue Red Green

Presentation Name Course Name Unit # – Lesson #.# – Lesson Name What is the length of the blue, red, green and purple. All answers in fractions and decimals