Observations & Measurements

Observations

Information gained through our five senses

Can be qualitative or quantitative

Types of Observations

Qualitative descriptionsColorTexture Formation of solids, liquids, gasesHeat changes - relativeOther non-numerical observations

Clear versus Colorless

Clear

See-through

Cloudy

Parts are see-through with solid

“cloud” in it

Opaque

Cannot be seen through at all

Words to describe transparency

Colorless does not describe transparencyYou can be clear & colored

Clear versus Colorless

Cherry Kool-adeExample:

Describe the following in

terms of transparency

words & colors

Whole Milk

Water

Clear versus Colorless

Cherry Kool-ade Clear & redExample:

Describe the following in

terms of transparency

words & colors

Whole Milk

Water

Opaque & white

Clear & Colorless

Types of Observations

Quantitative measurements - DataInternational System of Units (SI Units) are used

Quantity

Mass (how much stuff is there)

Unit

Kilogram (kg)

Instrument used

Balance

Volume (how much space it takes up)

Liters (L) Graduated cylinder

Temperature (how fast the particles are moving)

Kelvin (K) or Celsius (°C)

Thermometer

Length Meters (m) Meter stick

Time Seconds (sec) stopwatch

Energy Joules (J) (Measured indirectly)

Uncertainty in Measurement

Every measurement has a degree of uncertaintyThe last decimal you write down is an estimate

Write down a “5” if it’s in-between linesWrite down a “0” if it’s on the line

5 mL

10

15

20

25 mL

5 mL

10

15

20

25 mL Remember:Always read liquid levels from the bottom of the meniscus (the bubble at the top)

Example:Read the

measurements

Uncertainty in Measurement

Every measurement has a degree of uncertaintyThe last decimal you write down is an estimate

Write down a “5” if it’s in-between linesWrite down a “0” if it’s on the line

5 mL

10

15

20

25 mL

5 mL

10

15

20

25 mL

Example:Read the

measurements

It’s in-between the 10 & 11 line

10.5 mL

It’s on the 12 line

12.0 mL

Uncertainty in Measurement

Example:Read the

measurements

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

Uncertainty in Measurement

Example:Read the

measurements

1 2 3 4 5 6 7 8

1 2 3 4 5 6 7 8

It’s right on the 4.3 line

4.30

It’s between the 3.8 & 3.9 line

3.85

Uncertainty in Measurement

Choose the right instrument If you need to measure out 5 mL, don’t choose the

graduated cylinder that can hold 100 mL. Use the 10 or 25 mL cylinder

The smaller the measurement, the more an error matters—use extra caution with small quantities If you’re measuring 5 mL & you’re off by 1 mL, that’s a

20% error If you’re measuring 100 mL & you’re off by 1 mL, that’s

only a 1% error

Inference

Inference

Inference

We will cover:Data TablesLine GraphsBar GraphsCircle Graphs

We will cover:Data TablesLine GraphsBar GraphsCircle Graphs

As a student, you should be able to :

1. Interpret and read graphs2. Construct data tables3.Construct different types of graphs (line graphs, bar graphs, circle graphs)

When data is collected, it presented in a way that others can view and make sense of it.Often the data will be presented in a _________ or a _____. Data tables are a way of _________ the information. Graphs are _______________ that represent ______________.

data table graphorganizing

pictorial diagramsnumerical data

Interpreting GraphsInterpreting Graphs

Study the line graph and answer the following question.

1. What information is being shown in this graph?

This graph shows the effect of

different concentrations of fertilizer on the growth of three different

types of plants.

Study the bar graph to the right and answer the following questions:

1. Do fish grow to a larger weight in pond water or in tap water?

Pond water.

1. Do fish grow to a larger weight in pond water or in tap water?

Pond water.

2. Which grow larger, the males or the females?

Females

2. Which grow larger, the males or the females?

Females

Making a Data Table

Making a Data Table

As scientists collect data, it must be recorded in an organized fashion. Any time data is collected in an experiment, it is most often presented in a table. The data table must have a title, rows, columns, and heads. The title should be placed at the top and tells the observer what information is contained in the table.

Making a Line Graph

Line graphs show data plotted as points that are connected by a line. Line graphs are often used to show change over time and can be used to compare two or more sets of data.

The independent variable is the one being manipulated or changed during the experiment. It is always placed on the x-axis or horizontal axis.

The dependent variable is the observed/measured result of the independent variable being changed. The dependent variable is always placed on the y-axis or vertical axis.

Making a Bar Graph

Bar graphs are useful for showing

comparisons of data collected by

counting.

A bar graph has two axes, a horizontal axis and a vertical axis. Generally the horizontal axis is labeled and the vertical axis is divided by quantity. The data are not related so the bars do not touch.

Circle graphs are used less often in science reporting, but they are often seen in

newspapers and magazines.A circle graph is a

convenient way to show the relative sizes of the parts

that form an entire body of data.

Circle graphs are used less often in science reporting, but they are often seen in

newspapers and magazines.A circle graph is a

convenient way to show the relative sizes of the parts

that form an entire body of data.

Under what circumstance would each of the following types of graphs be best used?

a) Line Graph: Line graphs are often used to show change over time and can be used to compare two or more sets of data.

b) Bar Graph: Bar graphs are useful for showing comparisons of data collected by counting.

c) Circle Graphs: Circle graphs are best used to give the viewer an overall or broad picture view of smaller groups of data and how the smaller groups fit into the whole.

Compiled using a variety of Internet resources and slide shows created by science teachers