Significant Figures
An Interactive Internet Lesson
When working with scientific data it is important to have both accuracy and precision. Accuracy is how close a measurement comes to the actual dimension or true value of whatever is being measured. Precision is concerned with the reproducibility of the measurement. Scientists report measurements in significant figures. The significant figures in a measurement include all the digits that can be know precisely plus a last digit that must be estimated. Depending on the piece of equipment that you are using to make the measurement, the rule of thumb for estimating is: "Estimate to one tenth of the smallest division" marked on the instrument. Then record all the certain digits and the one uncertain (estimated) digit.
In this exercise, you will make measurements and record them in the proper number of significant figures. Follow the directions below. Complete the site, take the quiz then complete the questions on the worksheet.
I. Internet activity
1. Open the site: http://antoine.frostburg.edu/cgi-bin/senese/tutorials/sigfig/index.cgi
2. Read each page, answer the question and submit your answer. Continue until you have completed the tutorial.
3. See how well you have learned the material by taking a short quiz. Go to : http://antoine.frostburg.edu/chem/senese/101/measurement/sigfig-quiz.shtml
4. Take the quiz until you have answered all the questions correctly and understand the material.
5. Complete the exercise below.
6. Begin your homework problems in the text that are on the planner.
II. Worksheet
Read the information on significant figures in your text and use it as a reference. Complete the following exercise.
1. Determine the correct number of significant figures in the following measurements:
a. 123 m _____ e. 4.5600 g _____
b. 0.123 m _____ f. 0.078 g _____
c. 40,506 m _____ g. 1.07080 m _____
d. 980,000,000 km _____ h. 3000 m _____
2. Review the section on significant figures in calculations in your text. Do the sample and practice problems, then complete the following exercise. For additional help go to:
http://www.carlton.paschools.pa.sk.ca/chemical/Sigfigs/contents.htm
Record your answer using the correct number of significant figures and proper units.
a. 7.55 m x 0.34 m _____
b. 2.10 m x 0.700 m _____
c. 2.4526 m / 8.4 sec _____
d. 0.365 m / 0.0200 hr _____
e. 8432 m / 12.5 hr _____
f. 7 m x 1.22 m _____
3. Round off each measurement to three significant figures.
a. 87.073 m _____
b. 4.3621 m _____
c. 0.01552 m _____
d. 9009 m _____
e. 17,777 m _____
f. 629.55 m _____
Take the first 4 practice quizzes at the following website:
http://lrc-srvr.mps.ohio-state.edu/under/chemed/qbank/quiz/bank1.htm