Electronic rain gauge

Grandson has a project to make and use a raingauge. This will be based on a cut down drinks bottle, the mainstay of primary school science. It seems a pity to have to make individual measurements and then transpose them into electronic format for sensible use, and of course it would be interesting to measure rainfall continuously, rather than once a day for example. So I researched making a slightly higher-tech one that will report electronically. It could be based on a micro:bit, although I'm concerned about getting the data off the m:b in a sensible fashion. The obvious means are

• Bluetooth - doesn't require a physical connection, but does require some kind of application to connect/collect
• Serial - I have managed to connect a Serial-USB chip to one of the ports to receive serial info from a m:b, so it could be connected to something a bit smarter

I have also obtained some small neodymium magnets and a couple of Hall Effect detectors. This might be pretty challenging as well, as the HE devices are incredibly tiny!

Hall Effect sensors in container!

You can just see the contacts in the above picture - there are two in the container, and that's my fingertip for scale... I have small hands!

micro:bit speed trap or timing gate

An idea I liked on the micro:bit web site was the speed trap. Make a pair of timing detectors from aluminium foil strips, attach them to pins on a micro:bit, put some foil on the bottom of a model car, and run it between the gates. Then count milli/micro (!) seconds between triggerings.

Fynn testing the speed trap

In the picture you can see the alu foil strips, attached with double sided tape to the Lego Board. ("Lego Board - a large square plywood tray with 1/4 round moulding screwed to the edges, to prevent Lego falling off. This particular one is probably 35 years old!!). Micro:bit is running a very simple programme, shown below.

Micro:bit code

This doesn't actually work so well - I have removed the Speed calculation and display, as it appears that micro:bits only do integer arithmetic and so since the speed is < 1 m/s it only shows 0! So we're just taking the msec readings. It takes about 430msec to traverse the 0.5m track at the current angle to the horizontal. An opportunity to check gravitational constants?

Car with triggering aluminium foil

The car has a strip of alu foil (more double-sided tape!) attached to the bottom, with a spring made out of the backing from the tape rolled into a loose, springy roll that just pushes the foil onto the surface. Seems to work fine!

I shall take this to the Kode Klub next week, as an interesting demo of what's possible with a bit of thought. Fynn really enjoyed seeing it done, and hopefully had some idea about what was going on.

Starting with micro:bits

It's time to look at micro:bits again with Rivermead Year 6. How best to do that?

Lesson 1

Let's start simply. 

• A short PPT show on micro:bits
• How to connect them
• How you write and download code
• Some examples of things people have done with them
• Dish them out, get people connecting them
• A simple application or two
• Electronic Di(c)e
• Paper, Rock, Scissors

That should take up a lunchtime. Maybe get them to look at the examples, decide on one they want to pursue in subsequent weeks, note the requirements, and bring them the following week.

Lesson 2

Ideally, I'd have people participating in projects that would run for 2+ weeks. There are so many ideas, all visible on the micro:bit coding website.

2018 and still at it...

Last year was pretty successful, in respect of Code Club and equivalent.

• Taught Hawkedon Year 6 (3 classes, 4 hours each)
• Ran Kode Klub (as opposed to Code Club...) Jan - Easter 2017
• Worked with some Rivermead Year 4 children towards participating in the 2017 Code Challenge at Bulmershe - code a game to teach a younger child something from scratch, in pairs
• We came 1st and 3rd - not bad! Something stuck obviously...

So far 2018 (up to Feb) has seen

• Hawkedon Year 6 again
• Currently running Kode Klub
• Spent a lot more time on Scratch trying to get principles more ingrained
• Switching to micro:bit after half-term for a change
• Started working with New Town primary, initially doing a "Scratch sheep-dip" for their staff at the end of Feb, with the possibility of working with Year 4/5 in the Summer term

Maybe Rivermead will repeat their efforts, we'll have to wait and see.

Overall, I'm struck by how hard it is to inculcate the simplest Loops-Variables-Conditionals notions into pupils' heads. I think we need to do much more on more concrete things, which unfortunately don't have the immediate "ooh, it's a computer, let's hammer at it" attraction. Working through Flow Charts would be useful, preferably with some kind of real-world practical application e.g. making tea, getting ready for school. But "concrete is critical"!! I shall be emphasising that with the New Town staff.