Description and Measurement

Standards

• S8CS3e- Address the relationship between accuracy and precision.

• S8CS3d- Decide what degree of precision is adequate, and round off appropriately.

Essential Question

• Why is it important to be able to describe and measure with accuracy and precision?

Warm up

• Quick Write: Discuss times when you have used measuring tools

What is measurement??

• Measurement is a way to describe the world with numbers. It answers questions such as how much, how long, or how far.

Estimation

• Estimation can help you make a rough measurement of an object when you are unsure of the actual measurement. (This could happen when an object is too large to measure, or you do not have the proper equipment to measure the object).

• You can use comparisons to make an estimation. (Give me an example of when you could use a comparison to make an estimation.)

• http://www.brainpop.com/science/scientificinquiry/precisionandaccuracy/

What is the difference in Precision and Accuracy?

Precision

• Precision is a description of how close measurements are to each other.

Significant Figures(Sig Figs)

• The number of digits that truly reflect the precision of a number are called the significant digits or significant figures.

• Digits other than zero are always significant

• Final zeros after a decimal point (ex. 6.545600 g) are significant

• Zeros between other digits are significant (507.0301 g)

• Initial zeros are NOT significant (0.0002030 g)

Following the Rules

• For multiplication and division, you determine the number of significant figures in each number in your problem. This significant digits of the answer are determined by the number with fewer digits

• EX. 6.24 X 5.6 = 34.384

• For addition and subtraction, you determine the place value of each number in your problem. The significant digits of the answer are determined by the number that is least precise. (Or less decimal places)

• EX. 6.14 + 5.6 = 11.74

Accuracy

• When you compare a measurement to the real, actual, or accepted value, you are describing accuracy.

• Like in the video, a watch with a second hand is more precise, however if it is not set correctly, the readings will not be accurate.

Common Types of Measurement Property Metric Units English Units

Length Meters, kilometers Inch, foot, mile

Volume cubic centimeters cubic inches

Fluid Volume Milliliter, liter

Quart, gallon

Mass Milligram, gram, kilogram Ounce, pound, ton

Temperature degree Celsius (˚C)

degree Fahrenheit (˚F)

Measuring Tools

Figure 4. Long distance measuring tape

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Figure 1. Ruler

Figure 2. Flexible measuring tape

Figure 3. Caliper

Measuring tools cont…

Graduated cylinder, measuring cup, water velocity-meter, thermometer, analytical balance

Exercise: Measuring Tools and Units

• Which measuring tool and units you will use to measure: 1. Classroom

2. Desk3. Pencil4. A Bucket of water5. Your sibling