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Larry Dukerich's picture

Conceptual Chemistry

Wed, 11/19/2014 - 16:19 -- Larry Dukerich
BCA charts

In a recent contribution to ChemEd X "Stoichiometry is Easy", the author states that he has "vacillated over the years between using an algorithmic method, and an inquiry-based approach to teaching stoichiometry. " I would like to suggest that there is another approach to mastering stoichiometry and that it should precede the algorithmic one: it is the conceptual approach based on a particle model to represent the species involved in chemical reactions.

DAVID LICATA's picture

Stoichiometry is Easy

Sun, 11/16/2014 - 20:30 -- DAVID LICATA
Keep Calm Stoichiometry is Easy

This article describes a three week lesson plan for teaching stoichiometry using an algorithmic method. Two labs (one designed as a laboratory quiz) several cooperative learning exercises, student worksheets and guided instructional frameworks (forcing students to develop good habits in writing measures and doing problem solving) are included. The highlight of the lessons is the "chemistry carol" (based on Felix Mendelssohn's music for "Hark! The Herald Angels Sing") in which students recite a five-step algorithm for completing stoichiometry problems. While algorithmic processes may not always be best, I have found that there are many benefits to giving students a firm background and something to always fall back upon in one of the more challenging topics of chemistry. I believe that the good habits developed in this method of stoichiometry carry through to all the rest of their chemistry work, making it much easier to use inquiry-based methods when doing other advanced chemistry topics.

DAVID LICATA's picture

Stoichiometry Guided Instructional Activities with Guide Framework

Sat, 11/08/2014 - 21:40 -- DAVID LICATA
Initial framework for use with stoichiometry GIAs

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).

Time required: 

Each of the activity worksheets requires 40 to 55 minutes.

DAVID LICATA's picture

Mole Conversion Guided Instructional Activities

Fri, 11/07/2014 - 23:37 -- DAVID LICATA
Mole Converstion Guided Instructional Activity Preview

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.

Time required: 

Each of the activities requires about 40 to 55 minutes. The first one used usually takes longer, the last goes quicker.

DAVID LICATA's picture

Mole Conversions: 1- & 2-step with format

Wed, 11/05/2014 - 19:52 -- DAVID LICATA
Screenshot of a portion of the worksheet

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).

Time required: 

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.

DAVID LICATA's picture

Finding and Writing the Molar Mass of Elements [corrected]

Tue, 11/04/2014 - 20:09 -- DAVID LICATA
Finding and Writing Molar Mass Screenshot

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.

Time required: 

About 45 minutes.

DAVID LICATA's picture

Stoichiometry Fireworks Lab Quiz

Mon, 11/03/2014 - 21:39 -- DAVID LICATA
Ignition of sugar and potassium chlorate produces purple flames and sparks.

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.

Time required: 

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.

AACT: A Community for K–12 Teachers of Chemistry

Thu, 09/04/2014 - 14:28 -- Emily Bones
AACT

On September 2, the American Association of Chemistry Teachers (AACT) launched its official website, loaded with lots of resources and member benefits. If you visit teachchemistry.org, you will find many great tools that K–12 teachers of chemistry can use in their classrooms; the new online periodical, Chemistry Solutions; professional development opportunities; and a community for you, in addition to many other benefits.

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