8th Grade 1-6 Scientific Measurement & Math

​Science Root of the Day:

DO NOW: Infer what the example words mean in your lab manual.

Extra Credit: Find three additional words that use this root and write them and their definition in your lab manual (6 Points Max)

Scientific Measurement

Tallest or deepest?

It is a misconception that the tallest structure in the world must be built on land. Until 2008, the worlds tallest structure was the Petronius Compliant Tower, built on the Ocean Floor. Measuring 610 meters tall, this Oil Platform held the title until 2010, when the 828 meter high Burj Khalifa took the title of the tallest building in the world!​

Multiple Choice

A controlled Experiment

• Introduces Bias

• Tests several variables at once

• Tests one Variable and has limited bias

• Changes no variables

Lesson Objectives

• Describe the different measurements scientists make

• Convert between metric prefixes

• Perform some of the math equations used in data analysis

​Why Use a Standard Measurement System?

• If everyone measured using their own system, we would not be able to understand how people came to different values

  • If one person measures using the length of their foot and another uses the length of their hand, it is hard to compare

• Modern Scientists Use the SI System to keep measurements the same no matter where you are​

​The SI System Uses Metric

• The Metric System: a standard measurement system based on the number 10

  • Allows scientists to compare data and communicate with each other

  • Uses different units for different types of measurements

    • Meter

    • Liter

    • Gram

  • Prefixes tell you how many of each unit there are

SI Prefixes

• Sometimes, we measure things that are very large or very small and want to simplify what we are looking at

  • Do you want to write out 10,000 grams or 10 Kilograms?

• We can a simplify our numbers using metric prefixes

  • Based on increases and decreases by a factor of 10

Fill in the Blank

How many meters are in a Kilometer

Fill in the Blank

How many centimeters are in a meter

Fill in the Blank

How many meters are in a dekameter

Reorder

Rank the prefixes from largest to smallest

• Kilo-

• Hecta-

• deci-

• centi-

• milli-

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Fill in the Blank

A nickel weighs 5 grams. How many milligrams does it weigh?

​Length

• Length: the distance from one point to another

  • The base Unit is the meter

    • 1 meter=100 centimeters

    • 1000meters= 1 kilometer

• Length is measured with a meterstick, measuring tape, or Ruler

  • Should be measured from the Zero point for easiest calculation

Mass Vs. Weight

• Mass: the amount of matter within an object

  • Unless you do something to change an object, it's mass doesn't change​

    • The Base Unit is Grams

    • We tend to measure in Kilograms in the metric system

      • Small objects use grams

• Weight: The force of gravity acting on an object

  • The SI base unit is the Newton

  • Can change depending where you are in the universe

​Volume

• Volume: the amount of space an object takes up

  • For regular shapes :Calculated by multiplying Length x Width x Height

  • For Irregular Shapes: Calculated in a lab using a displacement method

  • Units include

    • Centimeters Cubed: cm³

    • Meters Cubed: m³

    • Liters: L

​Density

• Density: the amount of Mass in a given volume

  • D=m/v

  • For a material It is always the same, no matter how much of something you have

  • Water has a Density of 1.0

    • Anything less dense than water will float

Multiple Select

Look at the chart and select all the materials that will float in water

• Gold

• Corn Oil

• Ethanol

• Corn Syrup

• Table Sugar

​Time

• The SI Unit for time is seconds

  • Measured with a stopwatch

    • We will use the lab Chromebooks for this​

  • Divided into smaller units like milliseconds

​Temperature

• A measure of energy of particles in motion

  • When particles are moving quickly, heat is created and the temperature rises

• Base unit is Kelvin (K)

  • Starts at 0 and moves up

  • We will use celsius in this class because thats what our thermometers and probes read​

Grade 8 Science Ohio | Lesson 2.1

Multiple Choice

Density is a measure of how much __________ is in a certain volume

• Mass

• Temperature

• Time

• Length

Multiple Choice

There are 1000 meters in a _________

• Kilometer

• Millimeter

• Centimeter

• Decimeter

Multiple Choice

What happens to an objects mass if you take it to the moon

• It increases

• It Decreases

• It stays the same

Multiple Choice

True or False: Density Determines if an object will float in water

• True

• False

​What Math Skills to Scientists Use?

• When scientists do math they rely on several types of skills to help analyze their data

  • ​Estimation

  • accuracy and precision

  • Significant figures

• In addition to these skills, they rely on tools to help them interpret large amounts of data

  • mean

  • median

  • mode

  • range​

​Estimation

• Sometimes it is not possible to get a perfectly accurate number when collecting data

  • Something may be too small or numerous to count accurately​

• Estimate: an approximation of a number based on reasonable assumptions​

• Example: You have billions of white blood cells in your body, but you can't count every one

  • Doctors take a sample and count how many there are​ in that sample, and then multiply up to estimate how many there are in total to determine if you have an infection

​Accuracy and Precision

• Do not mean the same thing in science

  • Accuracy: How close a value is to the correct value

  • Precision: how close a group of measurements are to one another

• Scientists use both to determine how good their results are and to try to determine where they made a mistake

  • Can help determine if the equipment is faulty​

​Significant Figures

• The measurements we make are never completely precise

  • Example: You are measuring something and it falls between the lines on a ruler

• Significant Figures: show how precise a measurement is

  • Include all the numbers you can measure exactly + one estimated digit​

​Using Significant Figures

• Example: you put an object on your scale which reads 3.24 grams. you add that object to a beaker that has a mass of 20.559 according to the box

  • Our scale only measures up to two decimal places. we don't know if there are any other numbers after that 4

  • I​f we add the masses together, we can't assume that there is no digit being added to the 0.009, so we round our final value to the second decimal place because that is what we can be sure of.

Average/Mean

• Mean: The numerical average of a set of data

  • Add all the numbers up and divide by the total number of objects that you added​

  • Sample problem:

    • The data table shows the number of inches a plant grew every day for seven days. What was the average daily growth?​

      • Add together all the daily growth measurements

        • 0.94+1.38+8.43+3.31+0.03+0.19+1.45

      • Divide by the total number of measurements

        • there were seven days

Fill in the Blank

What was the average (Mean) daily growth for the plant? **Round to 2 decimal places**

.

Fill in the Blank

Henry has scored 72, 67, 82, and 79 on his math tests. What is his average test score?

Fill in the Blank

Calculate the average rainfall in South Bend.

.

Median

• Median: The middle value in a list of numbers

  • To Find: First, sort the numbers from least to greatest

    • For an odd data set: the median is the number right in the center of the list

    • For an even Data Set: Add the two middle numbers together and divide by two

  • Sample Problem: Find the median for the data table:

    • 0.03, 0.19, 0.94, 1.38, 1.45, 3.31, 8.43

      • Median is 1.38 ​

Fill in the Blank

Henry has scored 72, 67, 82, and 79 on his math tests. the median of his scores? Round to a Whole Number

Fill in the Blank

Calculate the median rainfall in South Bend. Round to one Decimal Place

.

Mode and Range

• Mode:The number that appears most often in a data table

  • Not all data sets have a mode

• Range: The difference between the largest value in a data table and the smallest value

  • In this Data table, the largest value is 8.43 and the smallest is 0.03

    • Range = 8.43-0.03= 8.4

Fill in the Blank

Henry has scored 72, 67, 82, and 79 on his math tests. What is the range of his scores?

Multiple Choice

To find the mean of a set of numbers you...

• Multiply all the numbers, then divide by how many numbers are in the set

• Add the numbers together, then divide by how many numbers are in the set

• Add the numbers together, then Multiply by how many numbers are in the set

• Add the numbers together, then divide by 10

Multiple Choice

Calculate the mean.

16, 5, 7, 12

• 9

• 6

• 12

• 10

Multiple Choice

On the semester final, Joe scored 85, Jill scored 89, and Bill scored 99. What was the average score for these students?

• 91

• 273

• 673200

• 31.5

​Reasonable and Anomalous Data

• When analyzing data, it is always important to ask if your data makes sense.

  • Sometimes you make a mistake in measuring

• Anomalous Data: Data that does not make sense or fit with the data set

  • usually caused by human or equipment error, but sometimes just exists

  • Example: A scientist measuring the wind speeds of hurricanes gets a measurement that says the wind was traveling 56 km/hr

    • The wind has to be traveling at least 119 km/hr to form a hurricane, so the scientists may check their mode of measurement to make sure it is working properly

Multiple Choice

Which bear in the chart shows an anomalous data point?

• A

• B

• C

• D

• E

​Percent Error

• There are some measurements that we know for a fact and never change

• When we test objects based on those amounts, we may get different answers

• Percent Error: A way of measuring the accuracy of your measurement

• Shown by the Following Equation:​

​Percent Error Sample Problem 1

• A student estimated the mass of a block to be 240 grams. When the block was put on a scale, the mass was 265 grams. What was the student's Percent Error?

  • Step 1: Identify your variables

    • Experimental: 240

    • True: 265

  • Step 2: Plug your values into the equation

Fill in the Blank

A student estimated the mass of a block to be 240 grams. When the block was put on a scale, the mass was 265 grams. What was the student's Percent Error? (Round to two Decimal Places)

-

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​Percent Error Sample Problem 2

• You do a lab and measure the density of quartz to be 2.45. The actual value is equal to 2.66. Calculate your Percent error

  • Step 1: Identify your variables

    • Experimental: 2.45

    • True: 2.66

  • Step 2: Plug your values into the equation

Fill in the Blank

You do a lab and measure the density of quartz to be 2.45. The actual value is equal to 2.66. calculate your Percent error

-

.

Multiple Choice

An archaeologist estimated that a fossil was 520 years old. It was actually 500 years old. What was the percent error?

• 4%

• 20%

• 3.8%

• none of these

Fill in the Blank

A zookeeper predicted that the weight of a newborn lion would be 2.8 pounds. When the zoo's lion gave birth, the newborn weighed 3.5 pounds. What is the zookeeper's percent error?

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