There are four interactive maps that are used as active learning experiences to enhance student understanding of dimensional analysis . . . . Maps 1 and 2 are shown for demonstration purposes.
- Map 1: Length, Area, Mass and Volume
- Map 2: Volume, Mass, Density, Moles, Molar Mass, and Atoms.
- Map 3: Map 2 is "duplicated" and placed to the right of the original Map 2 - the left side is Substance A and the right side is Substance B. The coefficient ratios from the balanced equation provide a "bridge" between Substance A units and Substance B units.
- Map 4: Molarity and PV=nRT is added to Map 3.
Many professors that use Chem21Labs have converted their first (and second) General Chemistry 1 labs into online, interactive Dimensional Analysis labs. The first dimensional analysis lab consists of 10 questions that require students to use Map 1 to arrive at the answers . . . the second lab contains another 10 questions and uses Map 2. The use of interactive dimensional analysis maps in lab has several advantages:
- Students are not ready for a wet lab.
- Students that miss the first lab can easily make it up because it is online. Also, the 2nd lab can be used to check-in to lab desks and work with Map 2 dimensional analysis problems.
- Students that have learned the ratio method in high school are forced to learn the factor-label method which will be invaluable to them in university science courses.
- The lab setting is a more intimate environment to help students who struggle with dimensional analysis problems. As the proficient students finish and leave the laboratory, more one-on-one help can be directed toward the remaining students.
- This is a perfect setting and a perfect time in the semester to help students become proficient with the use of their calculators - especially in entering numbers in scientific notation.
Map 1: Length, Area, Mass and Volume Map
- Click on the starting unit.
- Find a path between the starting unit and ending unit and click the units starting with the one adjacent to the starting unit.
- This sets up the factor-label part of the dimensional analysis problem.
- If the problem wanted you to convert 1.23 miles into fm, you would click on the following units in the order listed: mile, foot, inch, cm, m, fm. Notice that the units have been "set up" at the bottom of the map: it starts with mile and ends with fm and all the units cancel out except fm.
- In the "live" implementation, the student would click the Next button to open a web page where she would enter the "numerical part" of the conversion factors and the final answer.
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Map 2: Volume, Mass, Density, Moles, Molar Mass, and Atoms
Determine if the problem is asking you to report a numeric answer for a "1-unit" problem or a "2-unit" problem (density, g/mL or molar mass, g/mol).
- One Unit
- Click on the starting unit.
- Find a path between the starting unit and ending unit and click the units starting with the one adjacent to the starting unit. This sets up the factor-label part of the dimensional analysis problem.
- In the "live" implementation, the student would click the Next button to open a web page where she would enter the "numerical part" of the conversion factors and the final answer.
- Two Unit: If it is asking for density or molar mass, click the Two Unit button - this open a factor-label method in the numerator AND denominator at the bottom of the Map.
- Click on the starting numerator unit.
- Find a path between the starting numeratorunit and ending numerator unit and click the units starting with the one adjacent to the starting numeratorunit. This sets up the factor-label part of the dimensional analysis problem for the numerator.
- Click the Denominator button and repeat the previous step for the units in the denominator.
- In the "live" implementation, the student would click the Next button to open a web page where she would enter the "numerical part" of the conversion factors and the final answer.
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