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Reliable Results

Reliable Results

TEKS Objective

The student is expected to demonstrate that repeated investigations may increase the reliability of results.

Essential Understanding

The student uses scientific inquiry methods during laboratory and outdoor investigations.

Science Background

Sample Size and Multiple Trials: Holt, Reinhardt, and Winston (PDF) - Increasing the number of trials and the sample size in an experiment reduces the effect of random, uncontrollable variables on the results.  It also ensures that the experiment was completed and measured properly.  Read more about multiple trials in this excerpt from a science fair guide.

Sample Size and Multiple Trials
Holt, Reinhardt, and Winston, Think Central,

Data, Statistics: Visionlearning (website) - Detailed information on statistical terminology, the role of statistics in describing variability—and reliability—in data, as well as the relationships between variables. Includes references for further reading and additional learning modules.

Data, Statistics

Signature Lesson

Balloon Car: ZOOMsci/PBS Kids (PDF) - This simple, fun investigation demonstrates that repeated trials increase the reliability of test results, and that changing a single variable can impact the outcome significantly.

Balloon Car
ZOOMsci/PBS Kids,

Supporting Lessons

Flicking With Force: Utah Education Network (website) - Three balls of different mass are flicked with equal force and the distances they travel are compared. 

Flicking With Force
Utah Education Network,

Elaboration Lessons and Extensions

How Many H2O Drops Can Fit On a Penny? Science Spot (PDF) - Student investigate how many drops of water can stay on the flat side of a penny and average the data of multiple trials to obtain more accurate results.

How Many H2O Drops Can Fit On a Penny?
Science Spot,

Chain Gang: PBS Kids (PDF) - Students conduct an experiment to determine the relationship between mass and length of a pendulum and the time it takes to complete a swing.  Multiple trials are averaged to reduce the amount of measuring error and to ensure consistent results.

Chain Gang
PBS Kids,

Assessment Ideas

After completing one or more lessons on this page, make sure that students record their observations and calculations in their science notebooks. Have each student write a paragraph that describes how the results did or did not change as a result of repeating their investigations.

Literature Connections

What’s the Plan? Designing Your Experiment. Hyde, Natalie (ISBN-13: 978-0778751540)

Solving Science Questions: A Book About the Scientific Process. Chappell, Rachel M. (ISBN-13: 978-1600445422)

Related Science TEKS

(3.1A) Science Safety
The student is expected to demonstrate safe practices as described in the Texas Safety Standards during classroom and outdoor investigations, including observing a schoolyard habitat.

(3.1B) Recycling/Disposal of Science Materials
The student is expected to make informed choices in the use and conservation of natural resources by recycling or reusing materials such as paper, aluminum cans, and plastics.

(3.2A) Plan and Implement Descriptive Investigation
The student is expected to plan and implement descriptive investigations, including asking and answering questions, making inferences, and selecting and using equipment or technology needed, to solve a specific problem in the natural world.

(3.2B) Collect Data
The student is expected to collect data by observing and measuring using the metric system and recognize differences between observed and measured data.

(3.2C) Graphs, Tables, Charts
The student is expected to construct maps, graphic organizers, simple tables, charts, and bar graphs using tools and current technology to organize, examine, and evaluate measured data.

(3.2D) Analyze Evidence and Explain
The student is expected to analyze and interpret patterns in data to construct reasonable explanations based on evidence from investigations.

(3.2E) Value of Repeated Experiments
The student is expected to demonstrate that repeated investigations may increase the reliability of results.

(3.2F) Communicate Conclusions
The student is expected to communicate valid conclusions supported by data in writing, by drawing pictures, and through verbal discussion.

(3.4A) Tools for Collecting and Analyzing Information
The student is expected to collect, record, and analyze information using tools, including microscopes, cameras, computers, hand lenses, metric rulers, Celsius thermometers, wind vanes, rain gauges, pan balances, graduated cylinders, beakers, spring scales, hot plates, meter sticks, compasses, magnets, collecting nets, notebooks, sound recorders, and Sun, Earth, and Moon system models; timing devices, including clocks and stopwatches; and materials to support observation of habitats of organisms such as terrariums and aquariums.

(3.4B) Safety Equipment
The student is expected to use safety equipment as appropriate, including safety goggles and gloves.

Related Math TEKS

3.13A  The student is expected to collect, organize, record, and display data in pictographs and bar graphs where each picture or cell might represent more than one piece of data.

3.13B  The student is expected to interpret information from pictographs and bar graphs.

Additional Resources

Elementary School Design Packet: NASA eClips (PDF) - Introduction to a formal process for designing and testing a product or experiment to solve a given scientific problem.

Elementary School Design Packet
NASA eClips,

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