Presentation on theme: "Redesign AP chemistry exam"— Presentation transcript:
1Redesign AP chemistry exam Subsequent slides are excerpts from AP chemistry workshopEffective 2013 – 2014 academic yearSome 2013 – 2014 AP chemistry study guides may beinaccurate, i.e. do not reflect these changesIf you are using any AP chemistry study guides prior to 2013, somecontent do not reflect the redesigned AP chemistry exam
2Reducing Breadth of the AP® Chemistry Course: Student memorization of ubiquitous factoids out of the context of application is no longer a part of the AP® Chemistry curriculum framework.Instead, the AP® Chemistry framework focuses on increasing students’ depth of understanding of enduring principles for the purpose of application of skills to solve non- routine problems.Concepts no longer tested in revised course:Memorization of the exceptions in electron configuration of atoms and solubility rulesAssigning quantum numbersWriting nuclear reactionsDeriving the Henderson-Hasselbalch equationComputations of solubility as a function of pHMemorizing specific types of crystal structuresUsing standard enthalpies of formation to calculate the overall energy change in a reactionLewis Acid-Base TheoryThis illustration shows how the breadth of the new course is reduced. The topics listed have been eliminated from AP Chemistry course exams because they represent prerequisite knowledge. Overall, the course will focus more on students’ qualitative ability to problem solve and less on the minutia of quantitative functions.You can select the content that best suits your needs to teach the required concepts and skills. If you value these topics, you can still teach them. However, they won’t be tested.
3AP® Chemistry New Exam Design: Assessing the Learning Objectives Section Information: Item Types & WeightQuestion Types and DistributionTimingMultiple Choice-representing all Big ideas (50% of exam weight)60 multiple choice90 minFive Minutes Required Reading Time in Advance of the Free-Response SectionFree Response-representing all Big Ideas (50% of exam weight)3 multipart questions20-25 min per question4 single-part questions3-10 min per questionTypes of questions to be distributed among the single and multi-part questions:Lab 1: Experimental designLab 2: Patterns/analysis/selection of authentic data/observationsRepresentations 1: Translation between representationsRepresentations 2: Atomic/molecular view to explain observationQuantitative: Following a logical/analytical pathwayChapter 3: The examWhile the revised AP Chemistry Exam will still consist of multiple choice and free response questions, the number of multiple-choice questions will be reduced to approximately 60.All of the items on the new exam will be directly tied to the Learning Objectives. There will be no more guesswork about what will be tested on the AP Chemistry Exam.In a few minutes, you’ll see some sample questions, including some new question types. You will see how the new questions focus on student understandings of Big Ideas, Enduring Understandings, and Essential Questions – and do not demand memorization of facts.
4Particulate View Multiple Choice E X A M P L EParticulate ViewMultiple ChoiceCompoundMolecular StructureNormal Boiling PointDimethyl ether250 KEthanol351 KExam questions will no longer require students to recall factoids. Any essential facts that are not required content will be provided in the body of the exam question.Exam questions will be written to assess students’ skill with understanding content and with science practices.The question shown here assesses students’ proficiency with learning objectives 2.1 and Let me read those learning objectives now.2.1 Students can predict properties of substances based on their chemical formulas, and provide explanations of their properties based on particle views.2.13 The student is able to describe the relationships between the structural features of polar molecules and the forces of attraction between the particles.This item evaluates the content and science practices associated with these two learning objectives. It asks students touse representations and models to analyze situations or solve problems qualitatively and quantitatively (science practice 1.4)It has them make predictions about natural phenomena based on scientific theories and models and to connect phenomena and models across spatial and temporal scales (science practices 6.4 and 7.1).The structures and normal boiling points of dimethyl ether and ethanol are given in the table above. Which of the following diagrams best helps to explain the difference in boiling point of the two compounds?
5Real-World Application Multiple Choice E X A M P L EReal-World Application Multiple ChoiceOf the following metals, which would be the most appropriate choice for lining the inside of a railroad tank car used for transporting 1.0 M hydrochloric acid?MetalHalf-ReactionEºa)AlAl e– g Al–1.66 Vb)CdCd2+ +2 e– g Cd–0.40 Vc)CuCu e– g Cu0.34 Vd)ZnZn e– g Zn–0.76 VLet’s take a look at another sample test question from the new exam.In this case, students are evaluated on their ability to apply knowledge of inter-conversion between chemical and electrical energy in galvanic and electrolytic cells, the nature of a redox reaction, and the skill of estimating quantities to solve a real-world problem.Again we see students are being assessed according to the learning objectives which contain both content and science practices.This item assesses their knowledge of learning objective 3.13: The student can make qualitative or quantitative predictions about galvanic or electrolytic reactions based on half-cell reactions and potentials and/or Faraday’s laws.It also taps their knowledge of Science Practice 2.3 : The student can estimate numerically quantities that describe natural phenomena.
6Free-Response Section of the Exam Types of Free-Response Questions:Lab I: Engaging in experimental designLab II: Selection and analysis of authentic data/observations to identify patterns or explain phenomenaRepresentations I: Translation between representationsRepresentations II: Creating or analyzing atomic/molecular views to explain observationsQuantitative: Following a logical/analytical pathway to solve a problemThe free response section of the exam will contain different types of short and multi- part questions which:address all Big Ideas and thatfocus on the learning objectives which are more appropriately assessed by the free response question format
7Short Part/Representation II Free Response E X A M P L EShort Part/Representation II Free ResponseShown below are three models that can be used to represent a molecule of ammonia.Select one of the models. Indicate clearly which model you selected, and describe:one aspect of the ammonia molecule that the model represents accurately/well, and …one aspect of the ammonia molecule that the model does not represent accurately/well.In this question – an example of Representation II type free response, students must use knowledge and skills to connect the atomic or molecular view to a phenomena or observation.This free response question represents a short-part question with few scorable elements pertaining to students’ proficiency with two learning objectives – which assess students’ ability to use representations and models to analyze situations (Science practice 1.4), make claims and predictions based on models (Science practice 6.4), and connect phenomena and models across spatial and temporal scales (Science practice 7.1) in the context of chemical formulae, particulate views, and molecular geometry.The learning objectives tested are these: LO 2.21 The student is able to use Lewis diagrams and VSEPR to predict the geometry of molecules, identify hybridization, and make predictions about polarity.LO 2.1 Students can predict properties of substances based on their chemical formulas, and provide explanations of their properties based on particle views.As with other questions on the exam, it assesses their proficiency with both content and science practices.
8Multipart/Lab I (Experimental design) Free Response E X A M P L EMultipart/Lab I (Experimental design) Free ResponseDesign an experiment to collect data that supports the claim that a 1.0 M NaCl solution is a homogeneous mixture. Describe the steps, the data you would collect, and how the data support the claim. Laboratory equipment for your experiment should be taken from the list below. (You may not need all of the equipment.)50-mL beakersDrying ovenVolumetric pipets (5 mL, 10 mL and 25 mL)Hot plateStirring rodBalance100 mL of 1.0 M NaCl(aq)Fume hoodTo answer this question, the student will need to apply understanding of four different learning objectives (with four science practices). This free response question represents a multi-part question. It contains multiple scoring elements and addresses students’ proficiency with these science practices:Creating and using representations of phenomena to analyze a situation,Designing a plan for collecting dataAnd analyzing such data to identify patterns or relationships.It tests these within the context of these two learning objectives:LO 1.19 The student can design, and/or interpret data from, an experiment that uses gravimetric analysis to determine the concentration of an analyte in a solution.And:LO 2.9 The student is able to create or interpret representations that link the concept of molarity with particle views of solutions
9Multipart/Quantitative Free Response E X A M P L EMultipart/Quantitative Free ResponseA + 2 B D AB2The following diagram shows the change in concentration of the reactant A and product AB2 for the reaction represented by the equation above. The species A, B, and AB2 are gases.Indicate on the diagram where the reaction reaches equilibrium.At time t, what is the relationship between Q (the reaction quotient), and K (the equilibrium constant)?At equilibrium, what is the relationship between the rate of decomposition of AB2 and the rate of consumption of B for the reaction?For the same reaction at a different temperature, 6 moles of A and 9 moles of B are combined in a rigid 1.0 L container, and the system reaches equilibrium. If there are 3 moles of AB2 present at equilibrium, what is the value of K for the reaction at this temperature?Here is an example of a multi-part free response question that tests skills learned through lab investigations and through application of mathematical routines to solve problems. This question addresses four learning objectives which contain three different science practices.The learning objectives tested here are, in brief, that the student can calculate the equilibrium constant K from data.They can connect kinetics to equilibrium by using reasoning about equilibrium.They can analyze concentration versus time data.And they can, given initial conditions and the equilibrium constant K, use the tendency of Q to approach K to predict whether the reaction will proceed toward products or reactants.And again, both knowledge of science content and science practices is tested.
11Stimulus Stem Answer Choices Distractors Key This option (D) is correct. In steps 1 and 2, favorable intermolecular interactions are broken and this increases the enthalpy, corresponding to an endothermicprocess. In step 3, favorable intermolecular interactions are established, which decreases the enthalpy, corresponding to an exothermic process. (The sign ofthe enthalpy change for the overall process is established by the difference in magnitude between these enthalpy changes, and so the overall process can beeither endothermic or exothermic.)StemAnswer ChoicesDistractorsKey
12Identifying Differences between Legacy and Redesigned Questions Legacy ExamRedesigned ExamQuestions that test simple recall and memorizationQuestions that start with “which of the following is not”Questions whose answers include (A) I only, (B) II only, etc.Each question will address content and science practices within one or two learning objectivesEach question will have four options, not fiveNew exam will have question setsNew exam will provide normally memorized data in the stem if its neededNew exam will contain more particulate views of chemical reactionsFeatures
16What’s Out: Content Wise The first question is out, but it could be recast into a very interesting question to fulfill LO 1.13: Given information about a particular model of the atom, the student is able to determine if the model is consistent with specified evidence. [See SP 5.3]
17What’s Out: Question Type This content is still very much in Big Idea 2 with the differentiation of bonding in solids. We’d probably expect more data around this, but students need to be able to infer the type of bonding based on differences in electronegativity. For question sets, however, we would expect stimulus material to be data-driven, not essentially 4 multiple-choice questions with the same answers (i.e. matching). This question could be recast as a set if data on 4 unknown solids was given, and some more interesting questions than just inferring bonding type were asked.This question style is not okay (The I only, II only, etc.), but the content is still there.
18What’s Out: Content & Question Type Correct statements about alpha particles include which of the following?I. They have a mass number of 4 and a charge of +2.II. They are more penetrating than beta particles.III. They are helium nuclei.I onlyIII onlyI and II(D) I and III(E) II and III
21What’s In: Providing Needed Data in the Stimulus
22KCl dissolved in waterCH2Cl2 dissolved in benzeneEthanol dissolved in waterWhich of the following best describes the principal type of solute-solvent interaction in each of above solutions ranked in order from strongest to weakest solute-solvent interaction.(a)KCl in water-KCl is ionic; the main solvent-solute interaction here is the ion-dipole interaction(b)CH2Cl2 in benzene C6H6-CH2Cl2 is polar - it has the general formula AB2C2, so even though it is tetrahedral, it is polar.) Benzene is nonpolar, so the only interaction possible is the London dispersion interaction.(c)methanol, CH3OH, in water-There is a hydrogen bonding interaction between the hydrogen attached to the oxygen in methanol and the oxygen atom of water.In order of increasing magnitude, we have dispersion < H bonding < ion-dipole
23Build the Key/Distractors KCl in WaterIon to dipole interactionEthanol in WaterHydrogen BondsCH2Cl2 in BenzeneLondon Dispersion Forces(A)(B)KCl in WaterDipole to dipole interactionsEthanol in WaterHydrogen BondsCH2Cl2 in BenzeneNo solute to solvent interactions(C)KCl in WaterIon to dipole interactionCH2Cl2 in BenzeneLondon Dispersion ForcesEthanol in WaterHydrogen Bonds(D)CH2Cl2 in BenzeneLondon Dispersion ForcesEthanol in WaterKCl in Water