# Complex Numbers – Support for Calculations

I received a question on one of my Youtube video posts on the Casio Fx991 scientific calculator asking if it was possible to do complex number calculations on this calculator. The answer is of course yes – which then prompted me to make a quick video today on exactly how to do that with the fx991. See the video below:

This of course then made me think of our other technologies and that perhaps I should show how to do complex numbers with these tools as well.

Here’s the steps on the graphing calculators (any of the Casio models, since they all basically work similarly – the beauty of Casio, the buttons are relatively consistent). This example uses the CG50, but see fx-9750, fx-9860, etc).

And finally, on ClassPad.net, the FREE online math software that does it all – statistics, geometry, graphing, and of course calculations. (You can sign up for a free account (ALWAYS free) – here’s a quick how-to).

The question of course arises, when are we even using complex numbers? Or why do we need them? As I never really taught math content that required students to utilize complex numbers, I don’t feel I am able to answer these questions with authority, so I did a bit of research. For one, if we just go from a ‘content/standards’ perspective, if you are in states that incorporate The Common Core Math Standards (or a version of, whether renamed or not), then it is actually part of the High School: Number and Quantity standards which state, “Students will…”:

• Perform arithmetic operations with complex numbers
• Represent complex numbers and their operations on the complex plane
• Use complex numbers in polynomial identities and equations

But, that of course doesn’t really get at why do we need them. So here are some things I found in my search for this answer. I admit I can’t explain these any more than just listing them, but it at least points to places where complex numbers are in fact important and needed.

• Complex numbers are used in electronics to describe the circuit elements (voltage across the current) with a single complex number z=V+iI
• Electromagnetic fields are best described by a single complex number
• People who use complex numbers in their daily work are electrical engineers, electronic circuit designers, and anyone who needs to solve differential equations.

Hopefully this is helpful to those of you who are in fact doing complex calculations for whatever reason!

# The Power of Math Exploration

If I had a dollar for every time I hear “I would do more hands-on, inquiry, problem-solving, collaborative learning, in math class if I ________________________ (insert any one of the following):

• didn’t have as many students
• didn’t have to get through the ‘curriculum’
• had students who would actually talk
• if I didn’t have to make sure they were ready for the test
• if I didn’t have to review all the things they didn’t learn from last year…..
• ….the list goes on…….

I would be a very wealthy woman. What is mind boggling to me is there is so much research out there that shows students do better when they learn for understanding and not for memorization, which means learning through context, through inquiry, through problem-solving, through struggle. Time is one of the biggest ‘road-blocks’ teachers throw out there, and granted, there definitely is a time crunch to get all the content in before those dreaded assessments. What I try so hard to get across to the teachers I work with, is that you can  save time by taking time – you actually can ‘cover’ more ground by teaching from a more contextual, experiential, problem-solving way. As students make connections and problem-solve, they are able to learn more efficiently and more than one concept at a time because they are working from a connected-math view point instead of the single-skill/concept at a time approach we traditionally provide.

An example from Geometry: (this is using Classpad.net, free math software)

Concept – identifying polygons, and then what’s the difference between congruent-sided polygons versus regular polygons (identifying what a regular polygon is).

Activity: Using the drawing tool, have students draw examples of 3-side, 4-sided, 5-sided (and more….) polygons.  At least 2 of each kind that look ‘different’. Can be convex or concave

• Have students compare their shapes noting similarities and differences and coming up with definitions – attaching specific words to their definitions like convex, concave, closed, etc.
• Now have students use the arrow tool, and select one of their triangles, and the Adjustment menu to make all sides congruent. Then, choose a second triangle and Adjustment and make the shape a ‘regular’ polygon. What do they notice? Have them measure sides and angles and compare to others.
• Do the same for two different 4-sided figures (so Adjust congruent, then adjust regular), the 5-sided, etc.  Each time compare the two on their paper, and then compare to others, and try to come up with what the difference is between congruent-sided polygons and regular-polygons.
• Come to group consensus, and by the end of class students have manipulated, explored, collaborated and defined several things: polygons, convex polygons vs. concave, triangle, quadrilateral, pentagon,….regular polygon, congruent sides, etc.

An example from Algebra: (this is using CG50 Graphing Calculator (CG10 is similar):

Concept: Parent Function and Vertex From of a Parabola

Activity: Students graph the parent function of a Parabola (y=x^2) and then graph another in standard form using variables for coefficients.

• Have students use the modify feature of the graphing calculator to animate the different coefficients (one at a time)
• Observe what changes in that coefficient does to the parabola by comparing the modified to the parent
• Make conjectures and compare with other students till consensus is reached.
• Do this with all the coefficients.
• Have students then test out their conjectures by providing them several equations of different parabolas and, based on their conjectures, determine the shape, direction and location of the parabola BEFORE they do anything, and then test their guesses by entering in the calculator.
• Time saver: Doing this activity with linear equations first will then give students a general understanding of transformations of functions which they then extend and solidify with quadratics, which then can be easily extended into other equations, like the absolute value function. Time saver!

Obviously I am using technology here, because technology allows for conjectures to be made and tested very quickly. But technology is just a tool that is appropriate in some instances, but there’s so much that can be done without technology as well. You can make math much more of an exploration just through your own questioning (i.e. why do you think? can you explain that more? Are there other ways to do this?) and by providing students a chance to puzzle things out on their own, ask questions, use tools (so objects, paper, pencil, etc).

One of my favorite things to do is to provide them with a situation that has lots of information, but no question (basically, find a rich math task, but don’t give students the question(s)). Students then write down all the things they notice, such as quantities, relationships, etc. and then come up with their own wondering’s and questions. Then you let them choose a path they want to explore (this works well with small groups or partners). Usually it ends up that there are several different questions and solutions generated and explored using the same information. When students then share their findings, you find that there is a lot of math going on, which leads to some really interesting class discussions – some you yourself might not have thought of. You can then maybe even give them the question that might have been given in the problem – by that time students may have already explored it and if not, by now they have a real sense of what information in the problem will help them and they are more willing to actually solve the problem.

The key here – students only become problem-solvers if they are given the opportunities to explore math, make their own connections, and collaborate with others to verify their thinking. The more you give them opportunities and provide tools and resources and challenging problems, the more efficient they become at using math, connecting math concepts, and viewing math as a connected whole instead of isolated skills and facts. Take the time….it’ll come back in the end.

# Financial App (Pt 3 in series) – Let’s Talk About Money

With the holiday season upon us, and people often spending beyond their means, it seems appropriate to continue the CG50 (and all Casio Graphing calculators) app exploration with the Financial App.

One thing we do not spend enough time on in K-12 education is financial literacy. I know there are some states that are trying to address this, but it is not enough. This lack of understanding about money, savings, taxes, interest, debt, etc. is a huge contributor to our enormous debt crisis. Take our current political focus on the ‘tax reform’ bill that’s up for a vote soon – most people do not understand the ramifications of this because they don’t really understand anything about finances and how taxes work. We do not in this country teach the basics of financial literacy, which is why we have so many people drowning in debt, losing their homes, barely surviving month-to-month on what they make, and forget about having the ability to save for the future. How many students really understand about saving money? Or how taxes impact their hourly wages (i.e. \$10/hour is not that great when you factor in all the taxes taken out)? Or how not paying of your credit card monthly can make that \$300 dollar purchase become a \$400 or \$500 dollar purchase?

When I taught in Virginia, they started a Personal Finance course ‘elective’ (only for those students technically not on the college prep track – which was silly, as ALL students should take a course on Personal Finance). I was lucky enough to be the pilot teacher in my school, so I could pretty much create the course. My goal was to help students understand the importance of financial planning so they could survive and thrive in the world, no matter where their path took them. We started with learning about different career options they were thinking of, and what a typical annual salary might be (so plumber, electrician, hair dresser, doctor, lawyer, teacher, etc). They learned to fill out job applications, and write resumes, and then we ‘pretended’ they had been hired and were receiving biweekly payments (I actually gave them ‘checks’). We learned about payments, investing, taxes, rent, credit cards, insurance, amortization,balancing a check book (the class had a ‘bank’), etc. They had to determine where they would live, whether they would get a car, how much they could spend on food, entertainment, etc. based on their salary. What they quickly learned is that their wages, after taxes, were often NOT enough to do much else – no fancy apartment and having to make tough choices (i.e. gas or food, no car, no expensive smartphone, taking bus, walking, no movies every week, no fast food, etc.) When a student comes to you all excited about their \$9/hr job and all the things they will buy, and then realize after their first paycheck that it’s going to take months to have enough, it’s eye opening. And scary.

What I learned is that we do not talk to students about real-world, practical mathematics enough –  simple things like saving money, calculating tips, balancing a checkbook, interest, credit card debt, etc. This is math they need in their everyday life. This is math that has purpose. This is math that will help them make smarter decisions about their future. Maybe if we did, we wouldn’t have so many people struggling to survive or believing every unrealistic promise they hear in the news..

My message – let’s get some Financial Literacy into K-12 mathematics programs!

With that said, here is a quick video on the Financial App that is available on the Casio graphing calculators. This video uses the CG50.

# Summer Vacation – Use Your Experiences to Create Engaging Lesson Ideas

Sea Turtle at the Big Island, HI. How long do they live? How far do they travel??

I know most students and teachers this time of year are very familiar with Alice Cooper’s song “School’s Out for Summer”  (Seniors are probably focused on the line “school’s out forever….”  Maybe even some teachers!)  No doubt, summer is a time of rejuvenation for students and teachers – a much needed break, both mentally and physically. Note: Those of you who do not teach, and see teachers as having it ‘easy’ with the summers off, might try to spend some time in a teachers shoes before making those ridiculous assumptions, or read up a bit on what teachers actually do (they work more than 40 hours per week) and why summer breaks are so important.

Summer break is fast approaching for many, and some may have even started theirs. I remember those first couple of weeks literally not wanting to even look at anything related to school, students, or teaching. But – as most teachers will attest to, there comes a point where summer vacation weaves into professional learning or preparing for the next school year to begin. We never really turn off completely – we take classes to learn something new, or research some new technology or applications we want to try in class next year, or we revamp some lessons from the previous year. Summer vacation always ends up, at some time or other, connected back to teaching and learning – either personally for our own professional growth, or related to how we can be even better the next school year for our new group of students.

For me personally, everything I do always has me thinking of ways to create an interesting lesson for my students. It’s that pervasive idea that whenever possible, connecting the real world back to what students are learning will make the learning engaging and relevant. Just last week, sitting on the beach in Sea Isle City, NJ, watching this big machine out in the water that was dredging sand to replenish Avalon Beach, all I could think about were questions I would want my students to investigate.  Just a few of my questions, as I sat there:

• How much sand is being pulled up? Is it from the same spot (my observation, since the dredge is in a different location each day, is that no it is not)
• What happens to the sea animals and plant life that are ‘dredged’ up with the sand? Or, is there a filter that only allows sand in?
• What are the impacts on the sea life?
• How many hours a day do the dredges run? (seems like 24 hours to me!)
• How long does beach replenishment last? (if you don’t have any storms to wash it all back to sea) How long does it take to replenish a beach?
• How many pounds of sand is needed and where do they place the sand?

Lots of questions just from sitting and watching. What a great #STEM lesson this would be for students – there’s math, there’s science, there’s engineering and there’s definitely technology – it’s quite the endeavor. There is probably a ton of data out there and information about sand restoration projects, so you could have students researching, doing the math, checking out the science, investigating the machines used and the manpower needed. I did an initial search and found a couple articles already where I learned things like the grain size of the sand determines where the dredge pulls sand from (has to match the beach they are replenishing).  Pipelines are created to carry the sand from the dredge to the beach (so, how big are those pipelines? What happens after they ‘finish’ – do the pipes get removed?) Sometimes this is done to protect sea life, often times to protect commercial and residential properties, so this then begs the questions such as what’s the cost (money wise and to the environment), who benefits, what are the potential dangers and damage (to environment/sea life, etc). Here’s just a few articles I found.

My point here is not to give you a lesson on beach restoration. Instead, my point is that I was just sitting on the beach, enjoying my vacation, and saw the

Two clear streams in Costa Rica that when they meet, the chemicals in them react and turn the water blue. Why

machinery and started thinking. Posing questions. Realizing that there could be an amazing #STEM lesson here, which got me excited and doing research and yes – vacation or not – planning for teaching.  I think it is a natural tendency as a teacher to see a ‘lesson’ pretty much anywhere we go, which is what I want to emphasize here. Even on vacation, if you have a great idea based on something you are doing or seeing, some idea you think would be an engaging lesson, go with it. Take some pictures. Write down some ideas. Do some research. Use your own experiences and ‘time off’ to discover teaching ideas and spark your own enthusiasm for the next school year. Bring your vacation into your classroom and build relevant, real-world, multi-content lesson ideas that will spark student engagement, questioning, critical thinking and problem-solving.

Enjoy yourself and your summer, but never stop learning and looking for great ideas to bring back to your classroom.