Pinhole and schlieren imaging

Today I taught two classes this morning. After lunch I went back to Wenona School for another meeting with the Science Club students there. We continued working on the pinhole cameras we built a few weeks ago. At the time we ran out of tracing paper and made two of the boxes with tissue paper instead, which is both more fragile and also less translucent, so it was definitely not as good. Today we had more tracing paper, which we used to replace the tissue paper. We also trimmed one of the other boxes more neatly and stretch the tracing paper more flat across the opening.

After that, I helped start setting up a schlieren photography setup. We mounted a concave mirror on a retort stand with a couple of clamps, and then used a pinhole taped to a xenon bulb light to get a bright beam of light, and found the focal distance of the mirror and focused the light onto a screen next to the light source. For the next step we needed a knife edge and a camera, but time was running out and the lab assistants helping us couldn’t get them in time. So we left the remainder of the setup for next time.

Well be taking a two-week break for the end of term holidays, and then when we come back in three weeks hopefully we can finish it off and take some cool photos of things like the turbulence above a candle flame.

On the way back home I picked up Scully from my wife’s work, and then I had three more classes this evening. A pretty full day!

A new kitchen bin

The home mini-renovation proceeds apace. Today I went to the hardware store – a different branch, actually, in a further suburb. The store there is much bigger than the one near us. I went to get a new kitchen waste bin, small enough to fit into the cabinet space under the kitchen sunk. I got a 17 litre bin, only a bit smaller than the current 20 litre size.

When I got home I cleared out enough space for it under the sink and slotted it in. I didn’t even end up having to remove anything from under the sink – just rearrange it a bit. I took the old bin down to the garage and will discard it during the next household materials collection in a couple of weeks. The kitchen floor space now feels cleaner and more spacious.

I also checked for wood offcuts to make my new laundry shelf. I figured this larger store would have more offcuts to rummage through, but when I checked there were one at all! So I’ll continue my quest for the perfect offcut.

This morning I did a 5k run. And around lunch time another handyman came, this time to check our kitchen floor. It’s wooden parquetry, and in need of a sanding and resurfacing after years of scuffing. The guy measured it up and gave a quote for the work. He suggested we do it after the repainting we have planned for the end of October, because the painters may scuff the floor with stepladders or leave paint drips on it, so it’s better to resurface the floor after that.

This evening I did the first three critical thinking classes of the new Generation Gap topic. It’s an interesting topic, but the structure and questions are a bit more work for me than the last couple I’ve done. More thinking on my feet to run the class smoothly as we move through the topic.

Bathroom floor polishing and kitchen light installation

Today was a busy day – not only for me, but also for the two tradesmen who came in to do jobs.

The first one was a guy who restores stone surfaces. Our bathroom has marble floor tiles and they had become rough and pitted in places with age and various bathroom chemicals. one of the worst bits was this dirty looking stain, which I’ve tried cleaning but never managed to get out.

Marble floor stain removal

As part of the grand spring cleaning and mini-renovation, I’d booked a guy to come and polish the bathroom floor. He arrived at 8:00 and spent most of the day polishing and working on the floor, including inside the shower stall. It must have been back-breaking work. He ground the stained area to “open up the pores” as he said, and then used a chemical treatment to extract the stain. He also worked on the rough areas, mostly inside the shower stall, probably caused by various body wash and shower cleaning products.

The result at the end of the day is really good. The floor is silky smooth everywhere again, including the previously sandpaper-rough areas inside the shower. And the stained area is completely gone.

Marble floor stain removal

Very happy with this job!

The second person was an electrician, the same one we had install new ceiling lights for us a while back. We had been thinking about other jobs that we could get done, and my wife suggested getting some downlights installed in the kitchen, over the bench that sits in the cutaway section opposite the cooktop.

Kitchen before new downlights

In this view you can see the sink against the window wall. The cooktop is on the left side, just left of the knife rack. Opposite that is another bench, extending perpendicular to the wall, to the pillar you can see at far left of the photo. We often prepare things on this bench, and early on we recognised the need for more light here. So I installed a cheap fluorescent tube on the wall, which you can see above the microwave, with an ugly cord dangling down at an angle to the power strip on top of the microwave. It’s an ugly solution, but we’ve lived with it for years.

But my wife suggested we could get rid of it and install some downlights above the bench, maybe three running in a line inside the edge of the false ceiling that you can see above the kitchen. I informed the electrician what we wanted, and he said he could wire them to the same switch circuit as the main kitchen light. But we wanted them independently switched, so we could have them on or off separately from the existing kitchen light. He said he wasn’t sure if that would be possible until he arrived and had a look at the wiring.

When he got here this morning, he was skeptical at first. I wanted a new light switch in the place where our old copper telephone cable comes out of the wall, which is on that pillar at the far left – a convenient place for the downlight switch. I thought he might be able to run a new power cable up from there to the false ceiling cavity and do all the necessary wiring that way. But he said that he needed to tie it in to an existing light power circuit, and the only one suitable was the main kitchen light, which is switched from another switch on the opposite side of the kitchen entrance. Okay… but when he opened up that switch and looked at the wiring, he lamented that it appeared to have been run through the brickwork and concrete directly, without a conduit, which meant it might not be possible to pull a new wire through.

He aid he could try pulling the existing kitchen light wire through, tied to a leader cable, and then pull the cable back with two wires, and add the downlights to an extra switch on a new wall plate. But he said that if the cable was tightly restricted by the bricks and concrete, he might not be able to pull the new wires through, so there was a risk that we’d lose the cabling for the original kitchen light! I asked him to estimate the chances of that, and he said he could give the first step a try and if things felt like getting stuck he could try backing it out, and he felt that was low risk. So I said go ahead. Thankfully he managed to get the whole process done, although there was a tense moment when he was trying to pull the two new cables back through.

Here’s the installation of the new lights in progress:

New kitchen downlights

You can see two installed, and the third with a wire dangling out, and also wires dangling out the hole where the original main light was installed. And here is the finished job, with the original light and three new downlights all on.

New kitchen downlights

This view also gives you a much better view of the kitchen layout than the first photo above. After taking this photo I removed the old fluoro tube from the wall, which now looks much cleaner.

While the tradies were working on the bathroom floor and kitchen lights, I worked on writing my class for the next week of critical/ethical thinking. This week’s topic is The Generation Gap. It should be very interesting, asking kids to imagine thinking like adults and to discuss why people of different ages sometimes don’t understand one another.

Even though I didn’t do most of the hard work, it felt like a very accomplished day!

Sizing up a new kitchen bin

This morning I did my usual four online classes, finishing off a week of talking about Boredom with kids. It was actually a really interesting topic, especially discussing potential links between boredom and the ability to let your mind wander and be creative. It was clear most of the kids had never considered that possibility before, and thought it was a fascinating thing to think about.

At lunch I walked Scully to my wife’s work, where she spent the rest of the afternoon. I ran a 5k route home for exercise, and managed a decent time.

In the afternoon I inspected the cabinet under our kitchen sink, measuring it up to find what size of waste bin would fit under there. I think I mentioned earlier that we’re planning to replace the free-standing bin on the kitchen floor with one tucked away under the sink. I searched online for kitchen bins to see what sizes are available. It was hard picking one though, so I think I’ll need to take the dimensions of the available space to the hardware store, pick a bin that fits, and then come home and rearrange things to make space for it. I’d planned to do the rearranging today to make space, but realised it’ll be better to do it once I know what size bin we have.

This evening I have a day off teaching at the university, because it’s student study vacation week. I’ll be back next week to help students with their image processing projects.

Oh, and last night I watched Insidious: The Red Door on Netflix. I’ve been watching this movie series, and also The Conjuring series, and I finally realised why I keep getting movies from the two series confused. Because Patrick Wilson plays a lead character in both series!! The whole time through the movie last night I was getting vague feelings that this guy belonged somewhere else, not in this movie.

Cleaning the garage

This morning my wife suggested we go to a food and wine festival, which was being held at a suburb about 25 minutes drive away. Different parts of Sydney have various local festivals throughout the year, and spring is a favourite time for them. We got there early, just as it opened at 10:00, and it wasn’t too busy, which was good. It would have been crowded at lunch time.

There were food trucks and a couple of dozen stalls from different wineries showing off their wines and selling glasses and bottles, and several stalls with small businesses selling things like jars of jam, chilli sauces, sweets, nuts, etc. There were also some general market stalls selling handicrafts, clothes, plants, and so on. It wasn’t huge, and we walked around all the stalls in maybe half an hour. My wife got an açai bowl with fruit and grains. I considered getting some dumplings but the serving size was too large for a snack, and I didn’t feel like a full meal an hour before lunch time.

We came home via The Flour Shop, a bakery nearby which we’ve been to once before and it was awesome. It was again so today. I got a pastrami, jalapeño, and cheese pastry, which was delicious, and a coconut puff to take home for dessert tonight.

After getting home, I cleaned the garage. This is part of the overall ongoing spring cleaning leading up to the grand repainting of our home in October. We’ve been rearranging stuff and throwing things out and now we are moving some things into storage in the garage, so instead of just chucking it down there I thought we needed to clean it properly. I swept and vacuumed the garage floor, removing a layer of grimy black dust, then wiped down any horizontal surfaces on top of storage boxes and the steel cabinets we have in there, before throwing out some stuff and rearranging things to be neater and more compact.

It took about four hours of work overall, but now the garage is clean, as in not dusty, and also tidy. A tough job, well done. It was really dirty though, as I hadn’t given it a dusting for a few years. Real grime-under-the-fingernails dirty, requiring several hand-washings. And a lot of moisturiser afterwards to smooth the dried skin.

Gaming and sketching

Friday was planned to be me running my Star Wars roleplaying game one-shot adventure but I had to postpone it as previously mentioned. Instead we did a regular board games night. I offered to remain the host, but another friend volunteered his place so he could attend – he had to look after his kids, so couldn’t leave home, but he was fine to host board games. SO we had an extra player that way.

We played a new game for me: Bark Avenue. It’s a dog-walking game, played on a map of upper Manhattan, around Central Park. There is a deck of dogs, who live in various neighbourhoods and need different amounts of walking, come in three sizes (small, medium, and large dogs), walk at different speeds, and have different favourite activities (sniffing hydrants, playing ball, or splashing in water).

Bark Avenue

You need to pick up dogs, walk them around, perhaps picking up other dogs along the way, and then return them home after they’ve been walking for enough turns. Each dog walked is worth a varying amount of cash, plus you can get extra tips for taking a photo of the dog while out, letting it engage in its favourite activity, or making sure it poops. You have to be careful planning a walking route, because you need to pick up and drop off dogs in the right neighbourhoods, and various blocks have different activities available. Here’s a close-up of Darwin the beagle, showing the poop token to indicate it’s done its business.

Bark Avenue

It was pretty fun, though I came dead last! After that we played Codenames, and by that time we were done for the evening. Also on Friday I did the usual grocery shopping and teaching five online classes.

Today I made a Darths & Droids comic, and went for a 7.5k run. It was warm and sunny, not my favourite weather for running, but I managed it.

In the afternoon, my wife and I went for a walk over to Greenwich Hospital, to do some sketching of an old building there. Pallister House is an 1892 Late Victorian Filigree country home, which was later used as a girls school, then a girl’s orphanage, before finally becoming part of the hospital. When we got there, we found it very conveniently had several wicker chairs scattered around the area, so we grabbed two and set them up in front of the building to sketch it.

Pallister House, Greenwich Hospital

Later in the afternoon and into early evening, I started cleaning things up. We’re engaging in a huge spring clean prior to repainting the home in late October. We started weeks ahead because we have a lot we want to do. My wife has gone through a bunch of her stuff and cleaned it out, freeing up a stack of storage boxes, which I moved a lot of my Lego bricks into, which in turn freed up some plastic storage drawers. Into those went all of the tools from our under-the-skitchen-sink toolbox: screwdrivers, a hammer, spanners, hex keys, various plumbing tools and spare parts, screws and nails, tubes of glue and other stuff, and so on. The space freed up under the kitchen sink we’re planning to use for a new, smaller kitchen waste bin, to save space currently used by the large waste bin which stands on the kitchen floor. We still need to clean it out and rearrange things for optimal storage and then we’ll buy a new bin to fit the space.

Dealing with a company

My day was disrupted today by having to deal with a company doing something questionable. I don’t want to go into details, but it took a few hours to straighten out. I almost missed my first critical thinking class of the evening because of dealing with it too, but I managed to get home just in time.

This was time I had planned to spend preparing for tomorrow night’s Star Wars roleplaying game, that I’d arranged with some of my friends. The result was I didn’t have enough time to prepare, so I had to postpone the game. Instead we’ll assemble at another friend’s place for board games. I’ll have to run the Star Wars game another week.

That’s about it. It wasn’t a fun day.

Boredom

Today I wrote up my next critical and ethical thinking class, on the topic of Boredom. And this evening ran the first three classes. I think this is a good topic – defined as one where I have plenty of questions and they’re open-ended ones that get the kids talking and discussing reasons rather than just giving short answers. Samples:

  • Is boredom the same as having nothing to do? Is being busy the same thing as not being bored?
  • Why do you think some people get bored more easily than others?
  • Do you think people in the past (before phones, TV, or video games) were more bored or less bored than we are today?
  • Is boredom the fault of the person being bored? Or is it just something that happens to them?
  • Can boredom ever be useful?
  • Do you think animals get bored in the same way as humans?
  • What if, in the future, robots or AIs get bored?

I also did a science class and an essay writing class with two individual students. And in between I took some time to go for a walk outside, in the warm weather. It’s a nice change from the winter cold, but it feels too early in spring for weather this warm already.

Atomic theory prep

Today I mostly worked on a lesson plan and presentation for tomorrow’s online science class with my ongoing Outschool student. We’re heading towards basic atomic theory, after don some experiments with chemical reactions, and talking about the early experiments of 18th century chemists like Antoine & Marie-Anne Lavoisier. The goal for tomorrow is to get up to John Dalton’s formulation of atomic theory, and then leave some dangling questions that will lead into atomic structure in future weeks.

I did a 5k run after breakfast, before the day warmed up too much. Sydney reached 27°C today, and was 28°C yesterday – very warm for this early in spring. The mean maximum for September is only 20°C, but the forecast this week sees every day above that.

I went to pick up Scully from my wife’s work at lunch time. On the way I stopped to take a photo of this plant fibre snake thingy that is used to delineate the edge of a path through a park. Someone has put eyes on it, which makes it look amusing.

Path border critter

I stopped in at the local hardware store on the way home to look for that wood offcut I want to make a laundry shelf out of. But unfortunately when I asked to go through their offcuts bin, the guy told me that someone had just come in before me and bought everything that was in there! I looked and it was indeed totally empty. oh well, I’ll just have to keep trying until I find what I want.

Tonight I made calzones for dinner, with spinach and ricotta filling and some tomato sauce to pour over the top. I forgot to add some mozzarella to the stuffing, which I normally do, but they still turned out well.

Student image processing projects underway

Today was the usual busy Monday, with 4 ethics classes in the morning, then a bi of a break before heading into the city for the evening’s image processing session. The lectures are now over and we’re into the student project phase for the next few weeks. This is where most of the work for me is, where I spend the whole evening wandering around, checking how student groups are going, and answering their questions about the project in general or whatever specific image processing thing they’ve decided to work on.

For dinner before the session, I tried a place I haven’t been to before, called Yumko Korean Fried Chicken. They had a “lunch special” bento box which you could also have for dinner, with pieces of fried chicken, salad, rice, and a selection of three appetiser dumplings. It was really good, and very filling.

Yumko fried chicken dinner