Last Thursday (11/6/14) I attended a workshop on NGSS through our local RESA (essentially an ISD for the county/region). I’d like to touch on some of the things I took away from this workshop and will post again after the next follow-up workshops in December and March.
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This set of three worksheets are intended to be used as collaborative "Guided Instructional Activities" (GIAs). Two students cooperate to complete the steps of a stoichiometry problem, alternately doing parts of the process as they explain what they are doing and evaluate their partner's work. These worksheets emphasize an algorothmic approach that helps students learn to think aobut the purpose of a question, organize their work, set it up so that it is easily readable and can be followed by others, and make good use of "unit analysis" (dimensional analysis).
Each of the activity worksheets requires 40 to 55 minutes.
The three "Guided Instructional Activities" in this activity are three cooperative learning pieces in which students are guided through the process of converting from one unit to moles (or moles to a unit) by the method of "unit analysis" (dimensional analysis). Students alternate steps in the process and evaluate the success of each step. They must do things such as writing the given information correctly, finding the correct molar mass, setting up the mathematics correctly, and determining the answer to a required number of significant figures.
Each of the activities requires about 40 to 55 minutes. The first one used usually takes longer, the last goes quicker.
This worksheet asks students to do basic conversions of mass or molecules to moles and vice versa. The worksheet requires students to complete their work in a particular format and to inlcude number, unit, and chemical identity for each item in the "given," in each conversion factor, and in the answer. It gives students basic practice in this mathematical exercise while inforcing good habits that encourage "unit analysis" (or dimensional analysis).
This worksheet can be used as an in-class or as a homework assignment. The ten items on the first page should take 20 to 30 minutes. The ten items on the second page should take 30 to 50 minutes.
xkcd is a nerdy Internet daily cartoon that is written and drawn by a former NASA "roboticist". The subject matter is all over the map [yesterday's (11/4/14) is about TypographicChemistry], but tends to favor physics and computing. He encourages readers of the cartoon strip to send him outrageous questions, and he supplies outrageous but scientifically accurate responses. Some of the best of these have be come a surprising NYT Best Seller.
This worksheet is intended to be used as a "Guided Instructional Activity" (GIA). It asks students to find the molar mass of selected elements and write the molar mass as two equivalent fractions ("conversion factors") and as an equality. In each representation, students are forced to give the numeral of the measure, unit, and identity of the chemical.
About 45 minutes.
Given the amount of one reactant, students must use stoichiometry to find the ideal amount of the second reagent to use to create purple fireworks. The teacher ignites each groups' fireworks. Ideal mixture create little or no ash. Student assignment sheet with directions (and different initial amounts) plus teacher information and sample answers are included. This is an exciting and engaging activity that can be used as a stoichiometry quiz.
With one balance per table (two groups), the calculations should take about 10 minutes, the measures another 10 minutes. Ideally, students should be prepared to deliver their mixture to the teacher within 20 minutes. In practice, many students will take longer, particularly if the formula for potassium chlorate is not given and students are not familiar enough with ionic nomenclature.
The teacher will need about one minute per group to announce the group's mixture, ignite it, and wait for student responses. So if there are 15 groups, the teacher should allow about 15 minutes to ignite all the mixtures.
Students combine sodium carbonate and hydrochloric acid generating carbon dioxide gas which is allowed to escape. They measure the actual yield of carbon dioxide produced (missing mass), calculate the theoretical yield using stoichiometry, and then the percent yield. Students understand that 100% yield is the most appropriate answer (based on the Law of Conservation of Mass), so after considering the meaning of significant figures and the uncertainty of their measurements they are asked to decide if they did (or did not) get an answer that might indicate the validity of the Law.
One 50-minute period to perform the lab. One additional period to perform the calculations (optional). Often more able students will have time to begin some calculations at the end of the lab experiment.
Communicating the Value of Chemistry
The October 2014 issue of the Journal of Chemical Education is available online to subscribers [http://pubs.acs.org/toc/jceda8/91/10]. The October issue features sustainability; celebrating National Chemistry Week 2014 with articles on food and candy; increasing chemistry understanding for the nonscientist; nanochemistry; investigating materials: plastic & paper; exploring sound; research on chemical equilibrium instruction and student understanding of scale.
Advanced Placement Chemistry Special Issue
The September 2014 issue of the Journal of Chemical Education is available online to subscribers [http://pubs.acs.org/toc/jceda8/91/9]. The September issue features a special issue of 20 contributions on Advanced Placement (AP) Chemistry as well as many other articles to help students learn chemistry.