Tuesday, March 31, 2015

A New Site for Critical Thinking (wodb.ca)

Which One Doesn't Belong? Many of us have played with puzzles like that since we were very young. Most of those puzzles had one right answer. Christopher Danielson has been championing versions of this where every item could be the right answer. He's created a 16-page shapes book for young children, built on this principle. And he recently took it out to classrooms around Minneapolis, learning much about kids' understandings of shape.

Christopher's enthusiasm has engendered enthusiasm across the MTBOS (math twitter blog o sphere), and tonight I was able to attend a Big Marker online event discussing a new website dedicated to these puzzles: wodb.ca

What fun!

And so one more nifty tool is added to our techno toolbox for math class. (I have been loving desmos.com for a few years now, and use visualpatterns.org and estimation180.com whenever I get a chance.)

Saturday, March 21, 2015

Algebra Skills Needed for Calculus

Sam Shah posted his list here. I loved his list, but wanted to rewrite it a bit for myself. (Also, Sam finds it more effective to review the algebra ahead of time, while I think it's more effective to review once we see the need in our exploration of calculus.) I am posting this now, so it's available as an answer to this question on math educators stack exchange.

I teach my calculus course in an order that I think will help students learn. I have four units:
  • Unit 1 includes history, graphing functions, slopes of tangent lines by approximation, algebraically finding the derivative using the limit (which we do not carefully define yet), seeing the similarities between velocity, rate of change, and slope, average versus instantaneous velocity, derivative from a graph, (estimated) derivative from a table of values.
  • Unit 2 includes derivative properties needed for polynomials, graphing, limits and continuity, trig derivatives, and optimization.
  • Unit 3 includes chain rule, derivatives of exponential functions, implicit differentiation, derivatives of inverse functions (ln x, tan-1x), and related rates.
  • Unit 4 includes integration (finding area under the curve), anti-derivatives, fundamental theorem of calculus, and substitution method. If there is time we include volumes of rotation (which I think is a perfect ending for the course).

Algebra Skills needed for Unit 1 

  • Determine the equation of a line given two points, or a point and a slope, or a graph of a line, 
  • Find the average rate of change over an interval given a function or its graph, 
  • Clearly express what is happening to an object given a position versus time graph, 
  • Evaluate f(x+h) for any given function f(x), 
  • Rationalize the numerator (to find the derivative of the square root function) , 
  • Simplify complex fractions (to find the derivative of the 1/x function). 

Algebra with Calculus Concepts 
  • Approximate, using two points close to each other, the instantaneous rate of change at a point, given a function or its graph, 
  • Explain clearly why the procedure you used gives an approximation of the true instantaneous rate of change, 
  • Sketch a velocity versus time graph given a position versus time graph, 
  • Construct the formal definition of the derivative by modifying the definition of slope, 
  • Apply the formal definition of the derivative to simple polynomials and to simple square root functions.

Algebra Skills needed for Unit 2

  • Multiply out the expression (x+h)n (necessary to understand the proof for the derivative of y=xn),
  • Identify the holes, vertical asymptotes, x- and y-intercepts, horizontal or slant asymptote, and domain of any rational function,
  • Sketch the basic shape of a rational function,
  • Identify an equation for a rational function given a sketch of the function,
  • Explain clearly what a hole and an asymptote are,
  • Construct the equation of a piecewise function given its graph,
  • Sketch the graph of a piecewise function given its equation,
  • Work with inequalities,
  • Give both triangle and circle definitions of sin x, cos x, and tan x, and explain how they’re related,
  • Evaluate sin x, cos x, and tan x at all multiples of  π/6 and  π/4, without a calculator,
  • Understand trigonometry identities, including and sin(x+h)=sin x cos h + sin h cos x,
  • Accurately graph y = sin x and y = cos x.

Algebra with Calculus Concepts
  • Graph a polynomial or rational function, showing its maximums, minimums, and inflection points,
  • Follow complicated logic (in the definition of limit).

Algebra Skills needed for Unit 3

  • Understand composition of functions,
  • Use logarithm properties to “break apart” a single logarithmic expression into simple logarithms,
  • Understand properties of exponents,
  • Be able to graph exponential and logarithmic functions.

Algebra with Calculus Concepts
  • Think in terms of composition of functions to determine outer and inner functions, in order to use the chain rule.

Algebra Skills needed for Unit 4

  • Work with summations.

Friday, March 13, 2015

Copy Number One of Playing with Math

At 3:30 this afternoon, UPS knocked on the door and delivered copy number one of Playing with Math: Stories from Math Circles, Homeschoolers, and Passionate Teachers!

It is beautiful!

Now we put in the full order. Books coming soon...

If you haven't ordered your copy yet, you still can.

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