Netbooks on the road

My part of this “netbooks” trial involved much hair loss. Since the base for my work with disconnected teenagers is a cybercafé, there is no obvious rôle for a small, pocketable computer in the normal context of what I do. To make good use of the opportunity, I had to let these machines go out of my control, into an environment where small high value objects are regarded as currency. The sponsors said they were willing to take the risk of loss, provided that I took what I considered reasonable care to minimise it … what, exactly, constitutes reasonable care when handing expensive stuff over to teenagers who may not come back, have class A drug habits, and are due in court on Wednesday for handling stolen goods?

The other question was what exactly to do with these machines, to justify taking the risk. These two issues were linked; my clients had to feel that something worthwhile was going on, if they were to respect the tools involved.

One subject which interests all of them, regardless of gender, is cars. A month before the netbooks arrived, I started discussing with them the relationships between weight, power, speed and acceleration in a car. They have rather more practical understanding of these matters than can be easily explained by legal experience at their age so I concentrated on trying to relate this to theoretical engineering models, first visual and then symbolic.

With the netbooks on hand, I brought the talk around to how we might investigate the actual (rather than maximum or advertised) speed and acceleration values for real cars in daily use. They were very interested in this idea, and were keen to try their hand at using spreadsheets for the purpose. Then they realised that they would have to write down a lot of information and bring it back to the centre, then key it in, before they could do anything with it; at that point, disappointment and loss of interest threatened. Like a good conjuror, I then produced the netbooks.

Gathering data

The scheme they devised involved teams of six, each team stationed downstream from a Pedestrian Light Controlled crossing (this allowed two teams per crossing, getting double data for each red light, at three different crossings). The team leader (let’s call her or him “A”) would stand by the lights themselves, and would have the computer with an open spreadsheet. “B” through to “F” would be at measured distances downstream from the lights.

When the lights turned red (probably because “A” had pressed the button, but I didn’t enquire too closely), “A” would take up a position beside the frontmost car and enter details (make, model including engine size if possible, number of occupants) into the spreadsheet. When the lights went amber, “A” would raise his or her arm and the others would prepare to start stopwatches (mostly on mobile phones, though a few used the function on their wristwatches). When the lights turned green “A” would drop the raised arm and start walking up the line; the rest of the team would start the stopwatches running.

As the lead car passed each team member, the stopwatch at that position would be stopped. As “A” reached each, the time on their stop watch would be entered into the spreadsheet. In this way, a database of timings at fixed distances for different vehicles was built up. The results were also visible in a predefined scatter plot at the right of the same screen, with an interpolated trend line, so the model could be seen developing as they worked. When complete, the sets of data were merged into a single sheet on the desk top and then filtered to compare different data for similar subsets.

As for the risk, I handed over the complete trial set to the two alpha primes in the group (one male, one female) and left them to arrange distribution; and all came back.

Taking it further

This probably seems an underutilisation of the equipment. The same data collection could, after all, have been done with a pocket PC or similar (in fact, the idea was partly suggested by Chandra’s Big Freeze which used Psion clamshells. But the experience of taking “proper computers” out, and being trusted to do so, was worth its weight in gold and stimulated desire to learn. There were, in any case, two follow ups which would not have been possible with handhelds.

First, there was use of a pure mathematics package to compare the experimental data with a theoretical model. Chandra and AbsentCat had described their use of SysQuake LE for projectile modelling. SysQuake is available for both Windows (in the cybercafé) and Linux (on the netbooks) so I installed both. Having set up a basic acceleration equation (d=½at²) on the PC, we set the value of a by trial and error to give a line which matched the spreadsheet data. The young people found this very empowering, and probably learnt more algebraic confidence in half an hour of SysQuake than in all of their time with me to date. They also learned, to their surprise, that most acceleration is over within a very short time (with speed surprisingly low and surprisingly constant) on urban roads.

Second, AbsentCat scrounged us the loan of a set of plug in USB interfaces allowing various types of switch to start or stop timers on the netbooks. The students had a lot of fun with trying out various switching devices. We were loaned some pressure mats which could be placed on the road, though too often the passing vehicles avoided them. We experimented with home made trembler switches, but they were too sensitive, and hard to position usefully. Lengths of rubber tube, filled with water, were laid across the road with light pressure sensitive microswitches plugged into the ends – these were the most successful, and supplied 95% of our usable data.

Broader benefits

The tremblers were a complete failure in data collection terms but worth their weight in gold for the interest which they provoked. A drop of mercury is placed in the bottom of a glass tube; one electrode is immersed in it, and another arranged as a circular collar around the inside of the tube, fractionally above the meniscus; any motion which shakes the tube causes the mercury to make contact between the two electrodes, completing a circuit. Most of my clients have, at some time, been involved in vehicle theft, and immediately realised the relevance of tremblers to car alarms. We got a lot of chemistry, physics and engineering time out of the resulting investigations – even starting a new set of data collection exercises to investigate the link between tube size, collar spacing, and the trade off between sensitivity and discrimination.

This second (more accurate) phase gave us enough data to further investigate the mathematical model, and to extend it into areas such as mechanical work or power/weight ratios. It also allowed us to compare vehicles by type (small car, four wheel drive, bus, lorry, motorcycle, etc). Most valuably, in some ways, it led on naturally to discussing the range of road behaviours exhibited by different users of the same vehicle.

[Contributed by BobTheBumbler]

Polaris and me

I was going to review Polaris, a science fiction novel by Jack McDevitt. I’ve also been asked to write about what has happened to me since I reviewed Sunstorm as well. They have a lot to do with each other and I don’t think I can do them separately. So am doing them both together, and I hope it makes sense.

Before my English teacher recommended Sunstorm I was not interested in maths or science at all. In this essay I am going to save a lot of explanation by just using bold type to show things and ideas which are new to me since I started reading Sunstorm. I am glad that I was told to use a pen name, because if my friends knew I was writing this I would be socially dead forever.

After I reviewed Sunstorm, I read Donna’s review of Seeker. The thing that I liked most about Sunstorm was the idea of a planet being fired across space to hit a sun, like a stone being fired at a target with a catapult. Then my maths teacher showed me how to model this on a computer, and I realised that it’s actually more like firing the stone from a catapult in London and hitting a melon in Australia or somewhere. Anyway, Donna’s review mentioned that something similar happened in Seeker, so I read that as well.

I found that Seeker is the last book in a set of three about the same characters (the first is A Talent for War and Polaris is in the middle). So then I read the other two as well. All of the books have the same pattern: there is a mystery, the main characters discover it through something to do with the antiques trade, historical research gets them close to solving the mystery, and the mathematics of moving bodies finally gives them the answer. The mysteries are all different, and make you want to read to the end, but I won’t spoil them by describing them here - and anyway, it’s the maths bits that interest me (I never thought that I would hear myself say that). The historical research interests me too.

In Seeker the maths was about how a stellar system is affected by a brown dwarf star passing close by. In A Talent for War, it’s where a spaceship would be after two hundred years. And in Polaris it’s sort of like a cross between Sunstorm and Seeker because a small but super dense star called a white dwarf hits an ordinary G class star like our sun (not deliberately, it just happens) and goes straight through it and out the other side and destroys it.

I have got totally into this moving bodies stuff. I find the ideas exciting. My maths teacher has shown me how to find information about it and I have done a lot of reading. He has also shown me how to use a spreadsheet and a program called Autograph to set up and investigate my own models. I have learnt a learnt a lot but the the biggest thing I’ve learnt is that I have gone as far as I can without learning some pretty scary maths.

I have started studying some AS maths modules on my own. Well not really on my own because my maths teacher is helping me before school and my uncle is helping me at home but I mean not in a class or anything. I have completed module M1, which is the first mechanics module, and started on M2. Mechanics is what they call the sort of maths that will eventually let me cover orbits and trajectories and stuff (M1 and M2 don’t get that far, but I need to understand the basics). To understand some of the mechanics I need other maths, called pure maths, which doesn’t have anything necessarily to do with mechanics but you use it as a sort of way to describe things - my English teacher pointed out that it’s like I can only enjoy poetry if I can already read. So I’ve done quite a bit of P1 as well (that’s the first pure maths module).

I am using some software called Derive to help me with understanding the maths I am doing. There’s a lot of other software as well and none of it would be so exciting without the models which they let you build to try things out.

I’ve done a little bit of calculus with my maths teacher and my uncle. Calculus is when you imagine very small bits of a problem so you can get your head round it, then imagine that small bit happening over and over again, forever, to make it back into the big problem again but now you understand it. I haven’t explained that very well, but it’s important and it works. Its how you can start with the velocity of something, and the gravity of a star pulling it, and see where it will go, or the other way round.

By September I think I will have finished all three AS modules. My uncle says I could take the AS exam, even though I won’t have done my GCSE yet. But that would totally blow my cover and everyone would think I was a geek. My teacher says he’ll see if I can take it somewhere else that nobody knows me. I don’t know. I’ll see.

Doing all this other stuff has made me better in ordinary school maths and science too. I used to be rubbish at algebra, but now it seems easy. I know now that when you do experiments you do them lots of times and then look at all the results, not just one, and now the handling data part of maths makes sense too (but I don’t want to do the S1 statistics module cos that looks really scary).

My maths teacher has set up some experiments for me, like rolling a marble across a rubber sheet on a frame. You can poke your finger into the rubber, or put a lead weight on it, and pretend the dent is a gravity well and see what happens when the marble (which is supposed to be a lump of rock in space) passes near it at different speeds. And we tried firing an air gun through an egg in front of a video camera to see what might happen when the white dwarf goes through the G type star in Polaris, which is a physical model instead of the mathematical models which you do with pen and paper or with software.

I’ve started to think about what I want to do in my life. I am still most interested in literature and drama but I’m interested in other things too. I’ve been doing paintings and models from the shapes that all the trajectory models make, and imagined using them for stage sets - weird or what? I just tell my friends they’re abstracts. Because of these novels by Jack McDevitt I’ve got really into history as well, and I’ve seen the same sort of graph shapes in history books as in mechanics, like the way population grows looks like the way a rocket’s height changes as it takes off.

It would be nice to do everything, but I’m not sure you can. People seem to do one thing or the other. Mr Grant who organises this site and asked me to write about this stuff says he did literature as well as maths and sciences when he did his A levels but he’s quite old and I think things have changed since his day. He says that people who write books like Sunstorm and Seeker need to understand the maths and science as well as being able to write, and Jack McDevitt must understand history too, and I suppose that’s true. But A levels are a long way yet. I don’t even start my GCSE subjects until September.

Well, that’s a little bit about Polaris and quite a lot about what’s happened to me since I read Sunstorm. I hope it wasn’t too boring. And I hope nobody I know ever realises who I am.

[contributed by Lakshmi]

McDevitt, J., A talent for war. 1989, Sphere. 0747403333.
McDevitt, J., Polaris. 2004, New York, Ace Books. 0441012027.
McDevitt, J., Seeker. 2005, New York, Ace Books. 0441013295.
Clarke, A.C. and Baxter, S. Sunstorm: A time odyssey. 2006, London, Gollancz. 0575078014

Tackling the fear of algebra

The move from arithmetic to symbolic algebra is the biggest terror of secondary school mathematics, and many of our future scientists are lost over the edge at this fracture plane. Graphical work is popular but must support symbolic work, not pleasurably obscure it.

In an experimental programme, we encouraged a group of 13-14 year old students to record and express what they were doing in standard symbolic short-hand, and to share summaries of the results on an intranet web site. They were introduced to MathType, which was used not only for preparation of handouts but also for real time classroom explanations of simple, common sense events happening in Autograph.

MathType appealed to these teenagers. Its quality of output built their pride in their work; it was used to prepare their worksheets, and they had the experience of feeding back work of equivalent production values. Its ability to produce high quality web material gave them a high-status platform for displaying their achievements.

[Contributed by AbsentCat]

Graph magic!

Magic is a stage in the developmental history of science — a history which each of us retraces as we grow to intellectual maturity. Its study as such by eight-year olds was designed to meet criteria in cultural history and imaginative creation, but also as a context for strengthening critical faculties. The ability to rationally assess likely and implausible explanations of phenomena makes great strides at this age; separation of reality from model is central.

A link between mathematical models and spells, illustrated by Omnigraph, was well received and opened up a riot of speculative theorising. It also offered a new stage on which to parade the key concept of the algebraic “placeholder”.

Omnigraph is a graph processor, with facilities for investigating a number of mathematical areas up to very basic calculus. Equations or Cartesian coordinates, entered from keyboard or menus, are instantly reflected in curves, lines, points and shapes drawn in the graph window. Or, looked at another way, “spells” in the lower window produce magical results in the upper one - but rules can be deduced, even at this age, to predict the result of any given spell.

The mouse changes scaling, draws tangents, normals, areas, and the rest; curve drawing can be paused or abandoned, and in many cases the equation/spell is displayed as the mouse passes over a line.

A quadratic spell produces a passable model of the path followed by Harry Potter’s broomstick as he swoops to aid a Quidditch team-mate before returning to his normal altitude position. We can also play the part of the villainous Quirrel, interfering with the spell to alter Harry’s flight: alter one part of the spell (the m coefficient) to induce suicidal recklessness; change another (the constant c) to pull him out of the dive earlier - or cause him to crash!

If it looks like I’m getting carried away - well, perhaps I am. There is nothing more inspiring than watching young minds leap over their fears and years to grasp an idea. By the end of the morning, any member of the class could evaluate the value of y for any x, plotting the results on a graph paper Quidditch field. They could also deal implicitly with negative values for m and c, expressed as subtractions in a modified “spell”.

We assembled a tolerable Cartesian cartoon representation of Nearly Headless Nick, behind a transparent acetate screen overlay carrying a Hogwarts map. The pupils derived great amusement and insight from altering transformation matrix-spells to move Nick about the castle, expand him, shrink him, distort him in various ways…

Omnigraph is a simple, no frills program in its interaction with the user, which makes it very transparent in use. It is also well known; all the teachers involved had encountered it, if not used it, before. For more advanced work it could be replaced by Autograph; this would sacrifice instant usability in favour of added options. Both programs work well in conjunction with graphical calculators, for teaching at the levels where those are appropriate. Autograph offers stronger tools (eigenvalues, for instance), enhanced display options and statistical data plotting.

[Contributed by AbsentCat]