## New Chemistry Tools for LON-CAPA |

Numerical Problems |

In a numerical response problem the student enters a number as an answer, generally the result of a calculation of some sort. Complex numerical problems can easily be generated algorithmically by means of a Perl Script. A "tolerance" parameter can be set to specify how close the student's answer must be to be counted correct, and it can be "absolute" (mass within plus or minus 0.2 grams of the correct value) or "relative" (mass within plus or minus 2% of the correct value). Correct significant figures in the answer can be required, but the problem is not counted incorrect for the wrong number of figures. Instead the student is asked to correct the number of significant figures.

Numerical responses can involve units. If no unit, or the wrong unit, is entered, the problem is not counted wrong, but the student is told to correct the units. The computer will accept the answer in any of its accepted unit formats. For example, if the answer is **2.65 ft**, the computer will accept **31.8 in**.

To the right are just three sample problems illustrating these features, and they do not require units to be entered. They are presented with a "New Problem Variation" button at the top to allow you to explore the many randomized variations of each problem. Your responses are not recorded, and you have as many attempts as you like. To view these and additional sample problems as a student in the General Chemistry demonstration course, you must enter a username and password at the LON-CAPA Login page. (First you might want to read instructions at Getting Started with LON-CAPA.) You can get a username and password by contacting Robley Light at Florida State University. |
## ProblemsNumerical (Simple Stoichiometry-No Calculator Needed)Numerical (Stoichiometry) Numerical (Limiting Reagent) |