Pedagogy and the development of abstract concepts: the case of school mathematics Anne Watson Oxford 2013 Plan • Examples of school mathematical concepts to illustrate the endeavour • Examples of how processes of mathematical conceptualisation are described • Consideration of whether these are pedagogically useful • How is a focus on activity useful? What is a mathematical concept? • A mathematician would say that mathematical concepts are abstract structures that encapsulate relations, properties and behaviours of quantitative, spatial and axiomatically-generated objects – e.g. addition; functions • At school level some concepts can be understood through their real-world manifestations, so conceptualisation can involve inductive generalisation from examples (Marton), language (Sfard), mental images (Greeno), sense-making by reflection on action (Piaget), in several situations (Vergnaud). Addition actions: combining, counting, aggregating Growth of understanding • Aligning my understanding to the authority of the number system • Getting right answers Addition: relations a+b=c b+a=c c–a=b c–b=a c=a+b c=b+a b=c- a a=c- b Growth of understanding • Being able to adapt relations to create appropriate tools • Being able to decide how to solve problems • Getting right answers to problems Relations within isosceles triangles • Characteristics of defined class – equal edges (definition), learnt inductively through examples and definitions • Properties – equal angles (theorems) observed inductively through dynamic diagrams/example -> conjecture; deductively reasoned from theorems, proofs -> facts about new objects, or new characteristics about old objects Growth of understanding • Recognising structures/relations • Using properties to reason • Knowing what has to be true Which comes first? • The underlying relation? • The specific examples? • Generalisation is expressing an observed relation (ascent into talk from abstract) • Generalisation as imposing a pattern on a set of examples or actions or experiences (ascent from experience to abstraction) Theories • Piaget: action, invariant relations and representation • Vergnaud: fields/structures of • Greeno: structured spaces • Vygotsky: patterns of activity and talk in the figured world of mathematics • Sfard: syntax of communication: talk, diagram, inner talk Ways to describe mathematical concepts • Piaget: action and representation - > schema • Concepts in action and theorems in action (Vergnaud) • Concept is altogether a field of: a set of situations, a set of operational invariants (contained in schemes), and a set of linguistic and symbolic representations (Vergnaud) • Shift to: concepts ARE language and representations (Sfard, Janvier, Dorfman) • Schemes as grounding metaphors of action (Lakoff, Nunez) Growth of understanding (Pirie-Kieran) APOS theory/description (Dubinsky) • Piagetian ‘ascent’ model cf. historical development • Action (some kind of transformation – reflection on input-output relation of action) • Process (internal reconstruction that does not have to be performed – awareness of properties) • Object (the action itself becomes a mathematical object that can be acted upon) • Schema (principled linkages with other APO) Concept image – concept definition (procept) (Tall) • Examples, methods, words, symbols, situations, theorems .... etc. (experiences) • Related to Vergnaud’s idea of conceptual field but more concerned with experience of learners in educational situations • Formalisation: concept definition (convention) is alongside concept image – not above or below • Spontaneous and scientific concepts (internal connections of ideas) • Recognising that ‘tools’ remain to some extent perceived as tools, i.e. the contextual baggage that embodies the concept for a learner AiC – RBC (Dreyfus et al.) • Abstraction in context • Davydovian; analysis -> synthesis; “vertical mathematisation”/progressive refining of abstract ideas • Vertical reorganisation of students’ ideas through construction • Outcomes of activity become tools for later activity; development of an abstraction can be tracked through successive activity. • Relevant actions are epistemic actions – pertain to knowing – need to be observed to be pedagogically useful recognizing (relevant to this situation) (R) building-with (combine constructs to achieve goal) (B) constructing (new constructs) (C) • Kidron and Monaghan (2009) : ... with Davydov’s dialectic analysis the abstraction proceeds from an initial unrefined first form to a final coherent construct in a two-way relationship between the concrete and the abstract – the learner needs the knowledge to make sense of a situation. At the moment when a learner realizes the need for a new construct, the learner already has an initial vague form of the future construct as a result of prior knowledge. Realizing the need for the new construct, the learner enters a second stage in which s/he is ready to build with her/his prior knowledge in order to develop the initial form to a consistent and elaborate higher form, the new construct, which provides a scientific explanation of the reality. (p. 86-87) Negative numbers – manifestation problems The ‘ascent to abstraction’ model • Classification (what characteristics? what relations within objects?) (depends on variation offered) • Generalisation (what is typical and essential?) (depends on variation offered) • Definition and naming (necessary, sufficient and distinctive) • Abstraction, treating as a new object What is wrong with the inductive model? • Many concepts are not obvious; inductive reasoning from experience often leads to error or limiting assumptions. • Who decides what is worth generalising? • Who decides what characteristics are important? • Variation theory (Marton): the concepts we learn about are those that are presented through their variations, with learning involving discernment of variation and invariance Language • (Sfard) All we have is language and therefore conceptualisation is the use of language structures and syntax. The meaning of ‘multiply’ is how we focus on the similarities in a certain set of actions and phenomena. Cognition is communication. Functions • A relation between variables in which each input variable for which the function is defined is related to a predictable output variable h=ρt a x +5 x 0 1 2 3 4 y 2 3 6 11 18 Function representations x7 f(x) = 0 when x is rational, f(x) = x when x is irrational 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 Designing pedagogy Enactive – iconic – symbolic (Bruner; action -> representation) Manipulating – getting a sense – articulating (Mason; action -> relation -> expression) Constructionism • All we can do is provide constructive tasks which have purpose and utility. The utility is the conceptualisation – hammering is what we do with hammers and what we use them for; graphing is what we use graphs for; functions are what we use them for. Horizontal and vertical mathematisation (Freudenthal) • Focus on actions and solution methods in context • Provision of tasks that have similarity in underlying mathematical structure • Recognition of structural similarity in solutions/situations • Abstraction/ reorganisation/ “vertical mathematisation”/progressive refining of abstract ideas, then applying (ascent to concretisation) Growth of understanding • Agency • Alignment of concept image (my messy understandings) with concept definition (formal presentation) • Action • (pupil voice)