# CH.1 d-h - Variables, Data, & Analysis

The student will investigate and understand that experiments in which variables are measured, analyzed, and evaluated produce observations and verifiable data. Key concepts include:

d) manipulation of multiple variables, using repeated trials;

e) accurate recording, organization, and analysis of data through repeated trials;

f) mathematical and procedural error analysis;

g) mathematical manipulations including SI units, scientific notation, linear equations, graphing, ratio and proportion, significant digits, and dimensional analysis;

h) use of appropriate technology including computers, graphing calculators, and probeware, for gathering data, communicating results, and using simulations to model concepts.

Bloom's Levels:  Analyze; Understand

### BIG IDEAS

• Science strives to answer questions about the world around us through systematic observation and measurement.

• I can verify which brand of laundry detergent gets my clothes the cleanest.
• I can find the average temperature at which my microwave cooks food.
• I can tell if I baked cookies correctly.
• I can convert units, such as inches to meters.
• I can measure the pH of the water in a fish tank.

### UNDERSTANDING THE STANDARD

• Measurements are useful in gathering data about chemicals and how they behave.
• Repeated trials during experimentation ensure verifiable data.
• Data tables are used to record and organize measurements.
• Mathematical procedures are used to validate data, including percent error to evaluate accuracy.
• Measurements of quantity include length, volume, mass, temperature, time, and pressure to the correct number of significant digits. Measurements must be expressed in International System of Units (SI) units.
• Scientific notation is used to write very small and very large numbers.
• Algebraic equations represent relationships between dependent and independent variables.
• Graphs are used to summarize the relatinship between the independent and dependent variable.
• Graphed data give a picture of a relationship.
• Ratios and proportions are used in calculations.
• significant digits of a measurement are the number of known digits together with one estimated digit.
• The last digit of any valid measurement must be estimated and is therefore uncertain.
• Dimensional analysis is a way of translating a measurement from one unit to another unit.
• Graphing calculators can be used to manage the mathematics of chemistyr.

### ESSENTIALS

In order to meet this standard, it is expected that students will

e) read measurements and record data, reporting the significant digits of the measuring equipment.

demonstrate precision (reproducibility) in measurement.

recognize accuracy in terms of closeness to the true value of a measurement.

determine the mean of a set of measurements.

discover and eliminate procedural errors.

f) use data collected to calculate percent error.

g) use common SI prefixes and their values (milli-, centi-, kilo-) in measurements and calculations.

demonstrate the use of scientific notation, using the correct number of significant digits with powers of ten notation for the decimal place.

graph data utilizing the following:

•      independent variable (horizontal axis)
•      dependent variable (vertical axis)
•      scale and units of a graph
•      regression line (best fit curve).

calculate mole ratios, percent composition, conversions, and average atomic mass.

perform calculations according to significant digits rules.

convert measurements using dimensional analysis.

use graphing calculators to solve chemistry problems.

read a measurement from a graduated scale, stating measured digits plus the estimated digit.

h) use appropriate technology for data collection and analysis, including probeware interfaced to a graphing calculator and/or computer and computer simulations.

a, b, c, d, e, f, g, h, i, j)  make connections between components of the nature of science and their investigations and the greater body of scientific knowledge and research.

design and perform controlled experiments to test predictions, including the following key components: hypotheses, independent and dependent variables, constants, controls, and repeated trials.

predict outcome(s) when a variable is changed.

### KEY VOCABULARY

accuracy, base unit, conversion factor, density, derived unit, dimensional analysis, graph, Kelvin, kilogram, liter, meter, percent erroor, precision, scientific noation, second, significant figure

Updated: Nov 19, 2017