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Familia de Funciones con Variación Directa & Familia de Funciones con Variación Inversa

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Familia de Funciones con Variación Directa & Familia de Funciones con Variación Inversa

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Equation Solver - Instructions for Teachers

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This activity allows students to modify both sides of an equation and experiment to see how this changes the equation.

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The equation of a line with a known point and gradient assessment.

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The equation of a line with a known point and gradient assessment.

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Drawing graphs in the form y = mx + c part 2

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Drawing graphs in the form y = mx + c part 2

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answer' to the question posed in the problem is 3 dimes and 5 quarters - the point {3 dimes, 5 quarters} is plotted in the right panel - the point {8 coins, $ 1.55} is plotted in the left panel.] You can choose to set the number of quarters and dimes in the right panel by dragging the GREEN and BLUE DOTS,or - you can choose to set the $ value and the number of coins in the left plane by dragging the GREEN and BLUE DOTS. Study the two representations carefully - How are the number of dimes and the number of quarters represented in the {$ value, coin #} plane ? How are the value of the coins and their number represented in the {dimes, quarters} plane ? How are the quantities $/dime and $/quarter represented in each of the two planes? Which representation do you think provides you with more insight? Why?- How can you use this applet to generate more problems of this sort? - What questions could/would you ask your students? - What have you learned about word problems from this applet?

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answer' to the question posed in the problem is 3 dimes and 5 quarters - the point {3 dimes, 5 quarters} is plotted in the right panel - the point {8 coins, $ 1.55} is plotted in the left panel.]

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angles | angles | https://padlet.com/rdownes/angles
Calculus | cal | https://padlet.com/rdownes/cal
Circle Geometry | circle | https://padlet.com/rdownes/circle
Circular relations | cr | https://padlet.com/rdownescr
complex | complex | https://padlet.com/rdownes/complex
Cubic Functrions | cf | https://padlet.com/rdownes/cf
differentiation | dif | https://padlet.com/rdownesdif
Exponential functions | ef | https://padlet.com/rdownes/ef
Factorise | fac | https://padlet.com/rdownes/fac
Factorize | fac | https://padlet.com/rdownes/fac
integration | int | https://padlet.com/rdownes/int
Intergers | Z | https://padlet.com/rdownes/Z
Irrational Numbers | R | https://padlet.com/rdownes/R
Line geometry | line | https://padlet.com/rdownes/line
Linear Functions | lf | https://padlet.com/rdownes/lf
Natural Numbers | N | https://padlet.com/rdownes/N
Polynomial Functions | pol | https://padlet.com/rdownes/pol
Power Functions | pow | https://padlet.com/rdownes/pow
Quadratic Functions | qf | https://padlet.com/rdownes/qf
Rational Numbers | Q | https://padlet.com/rdownes/Q
Sinusoidals | sin | https://padlet.com/rdownes/sin
square | square | https://padlet.com/rdownes/square

# data[].attributes.body
angles | angles | https://padlet.com/rdownes/angles
Calculus | cal | https://padlet.com/rdownes/cal
Circle Geometry | circle | https://padlet.com/rdownes/circle
Circular relations | cr | https://padlet.com/rdownescr
complex | complex | https://padlet.com/rdownes/complex
Cubic Functrions | cf | https://padlet.com/rdownes/cf
differentiation | dif | https://padlet.com/rdownesdif
Exponential functions | ef | https://padlet.com/rdownes/ef
Factorise | fac | https://padlet.com/rdownes/fac
integration | int | https://padlet.com/rdownes/int
Intergers | Z | https://padlet.com/rdownes/Z
Irrational Numbers | R | https://padlet.com/rdownes/R
Line geometry | line | https://padlet.com/rdownes/line
Linear Functions | lf | https://padlet.com/rdownes/lf
Natural Numbers | N | https://padlet.com/rdownes/N
Polynomial Functions | pol | https://padlet.com/rdownes/pol
Power Functions | pow | https://padlet.com/rdownes/pow
Quadratic Functions | qf | https://padlet.com/rdownes/qf
Rational Numbers | Q | https://padlet.com/rdownes/Q
Sinusoidals | sin | https://padlet.com/rdownes/sin
square | square | https://padlet.com/rdownes/square
Factorize | fac | https://padlet.com/rdownes/fac

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Parallel Lines & Perpendicular Lines 平行線與垂直線

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Parallel Lines & Perpendicular Lines 平行線與垂直線

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Self Assessment in Equation of Straight Line Graphs

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This applet generates a straight line graph and the user is asked to enter the equation of the straight line generated.

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Linear Inequalities in Two Unknowns 二元一次不等式

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Explore linear inequalities in two unknowns.

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Quiz on Linear Inequalities in Two Unknowns 二元一次不等式：測驗

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Quiz on Linear Inequalities in Two Unknowns 二元一次不等式：測驗

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Comparing Equations of Two Straight Lines 比較兩條直線的方程

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Comparing Equations of Two Straight Lines 比較兩條直線的方程

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Abstract

This paper describes some of the research-based principles that I use when designing learning experiences to foster conceptual understanding. These principles are illustrated through the discussion of one type of experience: that of sorting multiple representations. I refer to learning experiences rather than tasks, because tasks are only one component of the design. Close attention is also paid to the role of the teacher in creating an appropriate climate for learning to take place.

After a brief excursion into my own theoretical framework, I describe the educational objectives behind my design and provide a detailed explanation of it in one topic, that of algebraic notation. This is followed with an explanation of the principles that informed the design and the evolution of the task. Finally, I briefly indicate how the design might be generalised to include other topics.

Introduction

My own designs for novel learning experiences are based on a three-way analysis of: the purposes they are intended to serve; the learning theories related to those purposes; and the empirically tested principles for design that emerge from these theories. Clearly, different learning theories apply when different learning outcomes are desired. A full analysis of these purposes, theories and principles is available in Swan (2006a).

There are perhaps five distinct purposes for learning mathematics: (i) developing fluency when recalling facts and performing skills; (ii) interpreting concepts and representations; (iii) developing strategies for investigation and problem solving; (iv) awareness of the nature and values of the educational system and (v) an appreciation of the power of mathematics in society (e.g. Cockcroft, 1982; NCTM, 1988; Stigler, Gonzales, Kawanaka, Knoll, & Serrano, 1999; Stigler & Hiebert, 1999). In the examples described below, my purpose is conceptual.

The learning theories I adopt for this purpose are derived from the social constructivists: concepts are co-created as language and symbols are appropriated and internalised ( Bakhtin, 1981; Vygotsky, 1996). Collaborative discussion is therefore essential. Other relevant design principles include the importance of focusing directly on significant conceptual obstacles ( Bell, 1993; Wigley, 1994); building on the knowledge students already have ( Black & Wiliam, 1998); creating tension and cognitive conflict that may be resolved through discussion ( Bell, 1993; A Bell, Swan, Onslow, Pratt, & Purdy, 1985; Brousseau, 1997); using tasks that are 'accessible, extendable, encourage decision-making, creativity and higher order questioning' ( Ahmed, 1987); using multiple representations to create connections ( Askew, Brown, Rhodes, Johnson, & Wiliam, 1997); and using tasks that allow students to shift roles and explain and teach one another ( Bell, Swan, Crust, & Shannon, 1993b).

These principles challenge many teachers' existing orientations towards mathematics, learning and teaching as outlined in Figure 1 ( Swan, 2005). A 'transmission' orientation in which explanations, examples and exercises dominate must give way to a more collaborative orientation in which students work together on 'interconnected', 'challenging' tasks; tasks that confront common difficulties. This model of learning should not be confused with that of "discovery" teaching, where the teacher simply presents tasks and expects students to explore and discover the ideas for themselves. Here, the teacher's role includes: assessing students and making constructive use of prior knowledge; making the purposes of activities clear; challenging students through effective, probing questions; managing small group and whole class discussions; encouraging the discussion of alternative viewpoints; drawing out the important ideas in each lesson; and helping students to make connections between their ideas.

Of course, principles guide rather than determine a design; the quality of the outcome also involves both creative input, based on prior experience and imaginative extensions from it, and systematic development through feedback from trials. These are much more difficult to describe.

In coming to understand a concept, a student must single it out and bring it to the forefront of attention (identify); notice similarities and differences between this concept and other similar ones (discriminate); identify general properties of the concept in particular cases of it (generalise) and begins to perceive a unifying principle (synthesise) ( Sierpinska, 1994). Working with teachers, I have developed five task 'types' that encourage these processes ( Table 1).

The educational objectives of the design.

I now describe a specific example of one of the task types, " Interpreting multiple representations". In this task, students sort cards showing alternative representations of algebraic expressions into sets, so that each set has equivalent meaning. In so doing, students must discriminate between commonly confused expressions and explain their differences. This task focuses on an aspect of mathematics content that is often taught, with limited success, in a mechanistic manner: the interpretation and manipulation of algebraic expressions. In particular, it involves: translating between algebraic expressions words, tables, and geometrical areas; recognising the order of arithmetic operations implied by conventional notation; recognising equivalent expessions; using the distributive laws of multiplication and division over addition. The design is taken from a nationally distributed resource for teachers ( DfES, 2005), and was developed as part of a research project with low-attaining 16-19 year old students in Further Education Colleges ( Swan, 2006a; Swan & Green, 2002).

An outline of the design

The preparation for the lesson involves enlarging and cutting out sets of cards (Figure 3) so that they may be easily viewed by groups of 2 to 4 students. Before beginning the task, the teacher asks students to respond to a few algebra questions on paper, without consultation. These answers are not discussed, but are put to one side. The teacher explains that they will be reconsidered to at the end of the session. The purpose of these is to help students become aware of any changes in their own thinking. These questions are of the form:

What does 4( x+5) mean? Does it mean the same thing as 4 x+5? If not what is the difference?
What does (5 x) ² mean? Does it mean the same thing as 5 x ²? If not what is the difference?
What does ( x+6) ² mean? Does it mean the same thing as x ²+6 ²? If not what is the difference?

Next, the teacher asks the students a few oral questions, to assess how well they can translate between words and symbols. Students present their answers using 'mini-whiteboards'. These are small, easily erasable laminated boards (Figure 2). Their advantage is that the teacher can rapidly assess many responses.

Show me an algebraic expression that means:
Add 7 to n, then multiply your answer by 3;
Multiply n by 3, then add 7;
Add 2 to n, then divide your answer by 4;
Multiply n by n, then multiply your answer by 4;
Multiply n by 6, then square your answer.

Students now work in groups. The set of cards (Figure 3) are presented in three stages.

First, students take it in turns to match the algebraic expressions to the written explanations. As they do this, they must lay the cards out side-by-side on the table. This activity forces students to attend to the order of operations. (So for example, students must discriminate between "Add six to n then multiply by two" from "multiply n by two then add six"). Students use the blank cards to produce additional expressions or explanations when they cannot find ones to match. Some students may notice that some expressions are equivalent, e.g. 2( n+3) and 2 n+6. This is not commented on this at this stage.

Secondly, students are given the cards showing tables of numbers. This time, there are no blank cards, but there are gaps in the tables that need completing. These ensure that students continue to make connections after matching.

Very soon, students complain that there are not enough of these cards for one-to-one matching and then, more slowly, begin to notice that in some cases, different expressions correspond to the same table, such as 2( n+3) and 2 n+6; ( n+6)/2 and n/2+3; (3 n) ² and 9 n ². At this stage, they have no explanation for this, it is simply an observation. The teacher encourages students to test these equivalences using other values for n, including very large numbers, decimal numbers and fractions: "Does this always match, even when you choose n = 250? n = 2.6? n = 1/3?"

Thirdly, students are issued with the area cards and match these to the other cards, using the areas of these pictures to explain why different pairs of expressions might be equivalent. They do this by arranging the matching groups of cards onto posters and writing explanations alongside (Figure 4). Throughout this process, the teacher prompts students to make connections between representations: "How can you see that this area matches this expression directly?", "How can you see that these words match this table directly?"

A plenary discussion is now held in which the teacher encourages students seeks to assess and generalise what they have discovered, using further questioning. For example:

Draw me an area that shows this expression: 2(n+3).
Write me a different expression that gives the same area.
Now draw me an area that shows this expression: 4(x-7).

Finally, students revisit their answers to the questions that were asked at the very beginning of the session and (i) correct their work, (ii) describe the causes of their mistakes.

Design principles that informed the design

The following principles have been developed from my own research and a recent consultation with 150 mathematics educators ( Swan, 2005; Swan & Lacey, 2008). These principles may be realised in the design, when it is faithfully implemented.

Teaching for conceptual understanding is more effective when we:

Confront difficulties rather than seeks to avoid or pre-empt them
Effective teaching challenges learners and has high expectations of them (Bell, 1993; Wigley, 1994). It does not seek to 'smooth the path' but creates realistic obstacles to be overcome. Confidence, persistence and learning are not attained through repeating successes, but by struggling with difficulties.We have built conceptual obstacles into this design. Expressions that are often confused, such as 3n ² and (3n)² are deliberately included to provoke discussion.

Expose and discuss common misconceptions and other surprising phenomena
Learning activities should expose current thinking, create 'tensions' by confronting learners with inconsistencies and surprises, and allow opportunities for resolution through discussion (Bell, 1993; Bell et al., 1985; Brousseau, 1997). The activity encourages misconceptions and alternative interpretations to surface so that they may be discussed. Conflicts originate both internally, within the individual and externally, from an individual's interpretation of another person's alternative viewpoint.

Make appropriate use of whole class interactive teaching, individual work and cooperative small group work.
Collaborative group work is more effective after learners have been given an opportunity for individual reflection. Activities are more effective when they encourage critical, constructive discussion, rather than argumentation or uncritical acceptance. Shared goals and group accountability are important. Teachers are advised to gradually establish 'ground rules' for discussion among students and then behave in ways that encourage dialogic and exploratory talk (Alexander, 2006; Mercer, 1995, 2000) (Table 2).

Give everyone a chance to speak.

Listen without interrupting.

Check that everyone else listens.

Try to understand what is said.

Build on what others have said.

Challenge what is said.

Demand good explanations.

Treat opinions with respect.

Share responsibility.

Try to reach agreement.

Make the purpose of the discussion clear.

Keep reinforcing the 'ground rules'.

Listen before intervening.

Join in, don't interrupt.

Don't judge or praise - this discourages contributions.

Ask students to describe, explain and interpret.

Do not do the thinking for the students.

Don't feel you need to resolve everything before leaving a group or before the end of the lesson.

Encourage reasoning rather than 'answer getting'
Often, learners are more concerned with what they have 'done' than with what they have learned. It is better to aim for depth than for superficial 'coverage' .Here, students are told that comprehension is more important than completion. The teacher's role is to prompt deeper reasoning by asking students to explain, extend and generalise: "Why is it true that 2(n+3)=2n+6? Can you produce an area diagram for 3(n-4)?"

The process of the design

In this section, I describe the process of designing the activity. The design presented here evolved from earlier versions, and no doubt will continue to evolve. In this case the final version (Figure 3) is similar to the first version (Figure 5) in many respects. The cards were originally devised to show combinations of symbols n, 2, 3, 6, together with pairs of operations add, multiply, divide and square. For each card, e.g. 2( n+3), an equivalent expression was devised, 2 n+6, so that equivalent expressions could be deduced. In addition, a distracter, 2 n+3, was introduced. Cards with the operations in the reverse order were introduced, so e.g. n ²+6 was accompanied by ( n+6) ². The area cards provided a spatial representation of these expressions. It was felt that students could review their knowledge of area while engaging with the task and use the areas to see why two algebra expressions might be equivalent.

The original version of the activity was in booklet form with advice to the teacher to make cards, if possible. When this was tried with teachers many did not take up this suggestion and they used the resource as though it were a textbook exercise. Students worked on the activity individually, in the order presented. The students wrote cryptic answers into exercise books like: 1-I; 2-F and so on. Towards the end of the session some teachers went through the answers using this notation and there was little discussion of the underlying concepts.

The original version suggested that the teacher should suggest that students substitute a number for n ( n=4) to help them search for equivalent expressions. On reflection this did not encourage students to think of the letters as representing variables. Thus tables were introduced.

The original version contained no blank cards. This led students to match the final few expressions using elimination strategies. On reflection it appeared much more profitable to encourage students to devise cards of their own. In addition, some spaces were left on the tables cards, partly to encourage students to engage in substitution and also so that matching would be less easy to spot. Interestingly, the tables now make it possible to use new strategies for matching. For example, students who recognised square numbers in the table could search for a square area. Students were also surprised to discover that several expressions could correspond to the same table.

Comparing the original design to the final one it will also be noted that:

Of the 12 algebra expressions in the original set, I have removed two simpler ones (9n ²); 2(n+6) and introduced two more complex ones (n ² +12n +36), n ²+6² along with some blank cards.

Of the written explanation cards, I have removed two: "Square n then multiply by 3" and "Divide n by 2 then add three".The diagrams are identical and the tables are all new.

The purpose of these changes was to challenge pupils in the following ways:

They must use the written explanations to construct the two easier expressions cards (9n ²); 2(n+6); and they already have two similar ones the teacher may refer to as a model (if this becomes necessary): (3n ²); 2(n+3)

They have to use the expressions cards to construct two easier written explanation cards: "Square n then multiply by three" and "Dividen by two then add three"; and they already have two similar ones to use as a model: "Squaren then multiply by nine" and "Dividen by two then add six"

They also have to construct two more complex written explanation cards: (n ² +12n +36), n ²+6²

The introduction of the two more complex expression cards also gives pupils the opportunity to distinguish ( n+6) ² from n ²+6 ² (an important realisation) and, as the little poster shows in figure 5a, they may also draw a diagram to show the difference. Secondly, they have a chance to look at the the equivalence of ( n+6) ² and ( n ² +12 n +36). So, in short they are presented with the opportunity to deduce that (n+6) ² is equivalent to ( n ² +12 n +36), not n ²+6 ², and give an explanation.

In conclusion, when designing the cards, I had to carefully consider:

The affordances and limitations of each representation;

How the cards would be used to expose common misconceptions;

The order in which the representations must be presented to maximise conflict and discussion;

The criteria that students will tend to use to match cards, and how I might minimise superficial matching;

The degree to which sets of cards can open up the possibility for generalisation.

Concluding remarks

The appendix to this paper displays two further card sets that I have devised to illustrate how this task-type may be used across the mathematics curriculum. Although such complex activities pose considerable management challenges for teachers, they have been extremely popular with both teachers and students and have strongly featured in three recent projects in which I have been involved (DfES, 2005; NCEE, 2006; NRDC, 2006). The evidence from these suggests the above task types have been popular with students, have improved learning outcomes and have also had an impact on the beliefs and practices of many mathematics teachers ( Swain & Swan, 2007; Swan, 2006a, 2006b, 2007).

The good thing about this was, instead of like working out of your textbook, you had to use your brain before you could go anywhere else with it. You had to actually sit down and think about it. And when you did think about it you had someone else to help you along with you if you couldn't figure it out for yourself, so if they understood it and you didn't they would help you out with it. If you were doing it out of a textbook you wouldn't get that help. After I did it I found that I used a lot of brain power, but I felt dead clever. Do you know that when you have actually done something and you actually put all your effort into something.. it makes you feel dead clever. I've told all my friends that I have actually done a bit of work in maths. 'Cause I never thought I was any good at maths, but I was alright with that. (Lauren, a 16-year-old low-attaining student).

Acknowledgements

This research was funded at various stages by The Esmée Fairbairn Charitable Trust, The Learning and Skills Development Agency, and the Department for Education and Skills.

References

NCEE. (2006). America's Choice: Mathematics Navigator. Washington, US.

NRDC. (2006). Maths4Life: Thinking through Mathematics. London: DfES.

Swan, M., & Green, M. (2002). Learning Mathematics through Discussion and Reflection. London: Learning and Skills Development Agency.

Appendices: Two further examples of multiple representation tasks

Example 1: Visualising and ordering decimals and fractions (DfES, 2005)

In this example, students are first asked to order a set of decimals into order of size. This exposes many misconceptions (e.g., size is related to the number of digits). They are then given area and/or number line diagrams to help interpret the numbers. Finally groups of cards are arranged in order of size. The whole process is repeated with the fractions and, over several sessions the six sets are combined.

Example 2: Frequency graphs, Cumulative frequency graphs, and Box and whisker plots (DfES, 2005)

This is an example of a much more demanding task, where students match frequency graphs, cumulative frequency graphs, and box and whisker plots, for large samples.

About the author

Malcolm Swan is Associate Professor and Reader in Mathematics Education at the University of Nottingham and has been a leading designer-researcher since he joined the faculty in the Shell Centre for Mathematical Education in 1979. His interests lie in the design of teaching and assessment, particularly the design of situations which foster reflection, discussion and metacognitive activity, the design of situations in which learners are able to construct mathematical concepts, and the design of assessment methods that are balanced across learning goals - and thus have a positive backwash effect on teaching and learning. Diagnostic teaching, using 'misconceptions' to promote long term learning, has been an ongoing strand of this work.

He has led design teams on a sequence of internationally funded research and development projects including work for UK examination boards and the US NSF-funded Balanced Assessment project and the Mathematics Assessment Resource Service (MARS). He has designed courses and resources for the professional development of teachers, evaluating their impact on student learning and on the beliefs and practices of experienced teachers. These materials have been sent by the UK Government and the Bowland Trust to all schools and other relevant educational institutions. In 2008 he was awarded the ISDDE Prize for educational design for The Language of Functions and Graphs.

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This paper describes some of the research-based principles that I use when designing learning experiences to foster conceptual understanding. These principles are illustrated through the discussion of one type of experience: that of sorting multiple representations. I refer to learning experiences rather than tasks, because tasks are only one component of the design.

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Reading Slopes from Equation of Straight Lines 由直線方程讀取斜率

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Reading Slopes from Equation of Straight Lines 由直線方程讀取斜率

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Steps in Finding Equation of Straight Lines 求直線方程的步驟

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Steps in Finding Equation of Straight Lines 求直線方程的步驟

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BLUE and GREEN are trains that travel from the Origin to the Destination. They can run as either slow trains or fast trains. The graph shows the next two trains.What problems could you generate using this applet? What questions could / would you ask your students to explore using this applet ?

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BLUE and GREEN are trains that travel from the Origin to the Destination. They can run as either slow trains or fast trains. The graph shows the next two trains.What problems could you generate using this applet? What questions could / would you ask your students to explore using this applet ?

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BLUE Inc. and GREEN Corp. are two companies that can supply the widgets that a company needs in its production. They each charge a fixed fee to enrol a company as a client.What problems could you generate using this applet? What questions could / would you ask your students to explore using this applet?

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BLUE Inc. and GREEN Corp. are two companies that can supply the widgets that a company needs in its production. They each charge a fixed fee to enrol a company as a client.What problems could you generate using this applet? What questions could / would you ask your students to explore using this applet?

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Quiz on Equation of Straight Lines 直線的方程：測驗

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Quiz on Equation of Straight Lines 直線的方程：測驗

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Equations of Parallel Lines and Perpendicular Lines 平行線和垂直線方程

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Equations of Parallel Lines and Perpendicular Lines 平行線和垂直線方程

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Quiz on Rectangular Coordinates (2) 直角坐標測驗2

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Quiz on Rectangular Coordinates (2) 直角坐標測驗2

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Simultaneous Linear Equations: Graphical Method 聯立二元一次方程：圖解法

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Simultaneous Linear Equations: Graphical Method 聯立二元一次方程：圖解法