Science Club: water

Today was my first visit to Brookvale School for the new school year. I had a new contact teacher there, after the teacher I worked with last year moved to another school. The new teacher organised a timetable for me, giving talks to the kindergarten and Year 1 and 2 classes, and also a 1.5 hour session with the new Science Club, for which she chose the students.

With the K-2 classes I gave a talk about the many different sorts of things that scientists do, including medicine, studying animals and plants to learn how they live, looking at rocks to work out where to dig for useful minerals, measuring volcanoes, drilling in ice to study the atmosphere from hundreds of years ago, astronomy, building robots, and making computer models of things. They all seemed fascinated to see all these different things, and the talk went pretty well.

For Science Club, the teacher initially gave me a list a few weeks ago, of 12 students. Only three of them were in the Science Club last year, so she’d clearly decided to give some new children a chance to participate. Then late last week she emailed me and said there were six other kids who were super keen to be in Science Club; would it be okay with me if they joined in? I said that would be okay.

I got there today, with a print out of the initial timetable the teacher had sent me, with the names of the original 12 students, but not the new six. As the kids filed into the library after recess, I asked them all their names, wrote name tags for them to wear so I could learn them, and also wrote down the names on my list.

I told them what sorts of things we’d be doing in Science Club, and then we started on some experiments. Today we were looking at properties of water. First up was looking at surface tension. I used an eye dropper to put drops of water onto a 5 cent coin on the floor, producing a bulging bubble of water, held on by surface tension. We counted how many drops I put on, before the bubble spilled and wet the carpet.

I explained to them how water was made of molecules of hydrogen and oxygen, and how the H and O atoms like to stick together, making an elastic skin on the surface of the water. Then we repeated the experiment, but with soapy water. This time the bubble was smaller, and I added fewer drops to it before it spilled. I explained that the soap had large molecules with one end that liked to stick to the water, but the other end pushed the water away. This made the skin weaker, explaining why the drop couldn’t get as large.

Next we did another experiment to look at surface tension. I filled a plate with milk and added drops of food colouring to the middle of the milk puddle. Then I got a cotton tip and dipped it in liquid soap… and touched it to the middle of the plate. I took a video:

Satisfying!

Next I got two glasses of water, one hot and one cold. I dropped some food colouring in each one, and we watched how it mixed into the water. In the cold water, the colour sank to the bottom and formed a layer below the clear water. In the hot water, however, it mixed evenly throughout. Then I explained to the kids that hot temperatures are caused by the molecules moving faster inside the water, and the faster moving molecules mix the colouring faster.

Finally we did an experiment in which I mixed iodine solution into water to make a brown liquid, and added some baby oil to form a clear layer on top. Then I shook the bottle to mix it all up, which encouraged the iodine to move from the water to the oil, in which it is more soluble. Doing so changes the colour to a bright purple, because the iodine colour depends on which liquid it’s in.

After a full day, I went home to relax. I typed out the names of the kids who I’d written down to send to the teacher, as a roll call. Then I noticed that the other timetable sheet she’d given my first thing this morning had the extra six kids’ names on it…

And the list of names I’d written down had three names not on that larger list. There were three extra kids in the Science Club who weren’t supposed to be there! I’m not sure if there was some sort of miscommunication, the kids thought they were in Science Club when they weren’t, or what happened. So I let the teacher know, and we’ll see what happens next time!

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In memoriam: Richard Hunstead

A couple of months ago I received an invitation from the University of Sydney to attend a celebration function for the career of my Ph.D. supervisor, Professor Richard Hunstead, as he retired. The date was to be Friday 14 February, with an afternoon of reflective talks by his colleagues, followed by an evening of drinks and canapés. I accepted the invitation.

Two weeks ago, I received another email from the University. Dick (as he was known) had suddenly fallen ill and passed away. The event would go on, now as a celebration of the life of this distinguished researcher. I felt less inclined to go to something where the mood would be so different, but yesterday afternoon I went.

I saw and spoke with many old university friends and teachers who I hadn’t seen in many years. The afternoon of talks consisted of reminiscences by several of Dick’s closest colleagues, a couple of whom had been fellow students with me back in the day. Many people who Dick had taught went on to very successful careers in astronomy – I felt a bit like the odd one out, having left astronomy and moved into a career in photographic research. But the crowd felt familiar, because during my years as an astronomy Ph.D. student I moved in the same circles as this distinguished group of people. The Australian astronomy crowd is a large family, and does some of the best astronomical research in the world.

Dick in particular had many achievements over his long career. Many I knew about, some mentioned by the speakers were new to me. In the early 1960s, radio astronomers discovered the strange radio source named CTA-102. Early observations indicated that the signal strength varied, and in 1965 Gennady Sholomitskii proposed that it might be a “beacon” set up by an advanced extraterrestrial civilisation. This was two years before Jocelyn Bell’s discovery of the first pulsar, which was also at first suspected to be an alien radio beacon – making it the first astronomical object seriously suggested as a potential sign of an alien civilisation. This caused a sensation in 1965, and The Byrds wrote a song about it, released on their 1967 album Younger Than Yesterday. Mount Palomar Observatory found an optical counterpart to the radio source, identifying it as a quasar, which removed the idea that it was an artificial radio beacon.

Dick came into this story over the next few years, when he was the first to observe CTA-102 at relatively low radio frequencies, using Sydney University’s Molonglo radio telescope. The received wisdom of the time was that variable astronomical radio sources only varied at high radio frequencies, in the GHz range. Molonglo observed at 408 MHz, well below the range that anyone thought radio variability occurred. With three years of careful observation, Dick showed that CTA-102, and three other sources, varied with time at this low frequency as well. This transformed our understanding of quasars and radiogalaxies, and laid the foundations for physical models of the processes that power these objects.

Molonglo Observatory Synthesis Telescope, east arm

[The Molonglo Telescope (my photo, during my honours year physics project, working with Dick).]

Dick was also a pioneer in the detailed study of the Lyman-alpha forest of absorption lines in the optical spectra of quasars. This is work that I know very well, as it was the subject of my Ph.D. thesis, working under Dick’s direct supervision.

AAT Dome

[The Anglo-Australian Telescope (my photo, where I did my observing during my Ph.D.).]

Besides his research, Dick was also passionate about education. He ran the second year undergraduate physics labs, and sometimes the first and third year labs as well, for many years, from when I was a student until fairly recently. He participated (as I learnt yesterday) in numerous education outreach programs, encouraging young people to pursue training in science, and collaborating with teachers and other groups to set up science education programs.

My last interaction with Dick was late last year, when I returned to the university for the first time in many years, to seek him out and request to borrow some lab equipment, for use in my own science education efforts with Brookvale Public School. I wanted some lasers and diffraction slits and other stuff to do experiments with my Science Club. Dick was keen to help and offered all the resources he had to give.

As I heard during yesterday’s event, this generosity of time and effort was repeated across the hundreds of students and colleagues who Dick mentored and worked with. The common theme to all the speakers was how Dick had boundless energy to share his enthusiasm for science with others and to actively encourage people, without prejudice, to develop their interest in astronomy. A good friend of mine told the story of how she, as a brand new first year undergraduate, ventured timidly into the astronomy department to ask if there was anything that she could do to participate in some sort of astronomy work. Normally only students in their fourth year are assigned research projects by the various physics departments, so a first year asking for additional work was very unusual. The first person she came across told her to go to biology because “that’s better suited to girls”. Undaunted she returned a few days later to try and find someone else. She met a professor in the corridor and asked the same question: was there some sort of astronomy project that she could possibly help out on? That professor was Dick, and he immediately gave her some real data, showed her how to book time on the computer system, and how to analyse it. That girl is now a professor in the same astronomy department.

Dick has left a huge legacy at the University of Sydney, in the Australian astronomical community, and in global research. Dozens, if not hundreds, of highly successful astronomers and scientists in other fields (e.g. me) owe their careers to Dick and his positive influence.

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School presentation and birds

This morning was the end of year Presentation Day assembly at the primary school where I do my volunteer science teaching stuff. As in the last few years, the school invited me to present the Science Award to the best science student. I get a reserved parking spot, and a seat on the stage with other special guests – it’s pretty cool. They present a whole bunch of academic, sports, and community awards to students, and “graduation” awards to the departing Year 6 class, going on to high school next year. This was the last time I’ll visit the school before the new year starts, and I wished the kids I saw from my Science Club a good Christmas holidays.

Afterwards, I decided to take advantage of being up on the northern beaches and took a walk for about an hour and a half around the Long Reef headland, which is a good spot to do some bird watching. I opened my account today with a crested pigeon:

Crested pigeon

I got a good shot of a red wattlebird (the bird isn’t red, it has red wattles, below the eyes):

Red wattlebird

And I managed to get a decent shot of a bird I hadn’t photographed before, a nankeen kestrel. It was flying overhead and I couldn’t tell what it was, silhouetted against the sky. I boosted the exposure and shot wildly, trying to follow it across the sky:

Nankeen kestrel

I could go on, but rather than post all the photos here, I’ve stuck them in an Imgur album with species IDs, which you can check at your leisure if interested. (They’re also in my Flickr stream, link below.)

I had some lunch nearby, and then drove a few minutes to Warriewood Wetlands, which is another bird hostspot, and photographed some more birds (also in the album). I got home just in time to take Scully out to the park for afternoon exercise. And then I spent the rest of the evening processing and uploading bird photos. 🙂

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Friday/Saturday Double

I missed yesterday’s post because I was out most of the day, so I’ll cover Friday and Saturday now to make up for it.

Friday morning I had a meeting at Standards Australia, chairing the committee on photography standards. I caught a train into the city, where Standards Australia has their offices in the Australian Stock Exchange building. So you have to check in and get a security pass, and the lifts have this weird operation where you swipe your visitor card and a lift comes and takes you to the floor you’re allowed access to, without you having to press any buttons – in fact the lifts have no buttons at all inside them.

We have committee members form various research and cultural institutions, as well as representatives form industry and professional photography associations. I reported on the work done at the international standards meeting in Cologne that I attended in October. One particularly interesting project is updating the formulation of visual noise measurement in photos, to revise the current international standard. Experimentally, the current definition doesn’t correlate very well with human observer opinion on how much noise is in an image. People from several countries have been doing experiments designed to derive and then verify a new formula based on image statistics – including an experiment that I ran in December 2018 (while I was still employed). The work is approaching the final stages and a revision of the standard should progress through the approval process in the next year.

After the meeting closed, I walked through the city to do some Christmas shopping. For someone I wanted to get some classic thriller movies, so I checked out a major retailer and their BluRay section. They had a bunch of Hitchcock films, and I thought I’d get Psycho and Vertigo. Both were available for $12.95, but Psycho had a discount sticker on it saying “2 for $20”, while Vertigo had a sticker “Buy 2, get 1 free”. I grabbed them and went to the counter and asked if they could treat the second sticker like the first and give me both titles for $20. The person said no, the stickered items were very strictly applied, and they couldn’t change the discounts. Feeling cheated of a bargain, I walked out empty handed.

A few blocks south, there was another shop of the same retailer, so I went in to see if their stick was any different. Again Psycho and Vertigo for $12.95, but here Vertigo had a “2 for $20” sticker, while Psycho had no discount sticker. If I’d managed somehow to get Psycho from the first shop and Vertigo from the second, I could have had them both for $20! But at this shop they again refused me the combo discount, so I stubbornly refused to buy either of them. If the stickers are “strictly applied”, how come the same titles are stickered differently at different shops??

Anyway, I progressed through a series of other shops, buying gifts along the way. The shopping areas were moderately crowded with Christmas shoppers, but not as bad as it’ll get in the next few weeks. Then I headed home on the train again. The sky was very grey and smoky still from the bushfires, but it seemed higher up, and not clogging the ground level with smoke like it had on Thursday.

After a brief stop at home, I set out for fortnightly Friday games night at a friend’s place. We started early, to give us an hour and a bit to write some Darths & Droids comics, at which we made good progress, writing four new strips. We’re still finishing off the Muppet storyline, and haven’t started work on The Force Awakens yet. We’re planning a group viewing of The Rise of Skywalker when it’s released in a couple of weeks, after which we’ll sit down and figure out our storyline through the final three films.

Then it was into games! We started with The Quacks of Quedlinburg, in which each player is a quack doctor, brewing magic potions in an attempt to sell them to suckers patients, in order to buy more ingredients to make more profitable potions:

The Quacks of Quedlinburg

This game was interrupted a bit by several of us veering off to play Magic: the Gathering games to complete the high-powered cube draft we started back in September. The final few games were completed, and Steven ended up winning, while I managed to come dead last, despite being the only person who knew in advance what cards we were going to be playing with! While this was going on, other players played hot seat in the Quacks game, taking over as other people subbed out to play Magic. I started the game in one seat, but returned later to take over another seat, from where I managed to come second in the game – while the seat I started in came last!

After this, we split into two groups to play two different games. I ended up playing Wingspan, which I’d never played before. It’s a game of collecting different birds, using food to gather them, and then they lay eggs, and various other things happen that score points.

Wingspan

This was two rounds in; I was playing the board at the bottom with the red cubes, and I thought I was going rather poorly. But by the end of the game:

Wingspan

I had a lot of birds, with a lot of eggs. My birds were not worth many points compared to the other players, but I had so many eggs that I won the game by 3 points! (89 on the score sheet in the photo.) It was a fun game, and I’m definitely keen to try it again.

The other guys were all ribbing me during the game, saying I’d find factual errors or stuff on the bird cards, since I’m interested in birds. I don’t recall the details, but I certainly made some erudite bird comments during the game, which only served to prove their point!

I got home late, so didn’t make a post last night. Today, Saturday, I spent the morning cleaning the bathroom and then making one of the new Darths & Droids strips that we write last night. And then after lunch my wife and I went out with Scully to a market, to meet her mum and sister there. Scully got to chase ducks and geese, which I don’t think she’s seen before. The geese were three times her size, but she was keen to chase them! The market ate up the afternoon, and then this evening we went out for dinner at a Greek place near us – that was established in 1969, so is celebrating its 50th anniversary this year.

Today was warmer, and the sky a smoky grey all day. This smoke is really starting to get to people, me included. It feels like we haven’t seen blue sky for weeks. And the outlook isn’t good either, with forecasters saying it will most likely hang around Sydney for weeks, if not months. Blah.

New content yesterday:

New content today:

Man 0 – Nature 3

Remember last Tuesday, when we had that incredibly intense but short storm? And it blew over my chilli plant, and I spent hours cleaning up the mess and repotting the plant?

This morning I woke up, and the chilli had been blown over again by strong wind during the night, spraying the new soil all over balcony. I quickly collected as much as I could with a dustpan and broom, and returned it to the pot. The plant is now leaning over again, so I’ll have to re-insert the stake and tie it up to hold it vertical again. But I didn’t have time to do that in the morning, because I had to leave to go the school where I talk to the kids about science, and run the Science Club.

Today I had the older classes, from year 3 to year 6, and I did a general Q&A session with them. They had a lot of good questions today, on a variety of topics, covering astronomy, chemistry, biology, physics, and geology. I talked through most of the answers, but a couple I had to admit I didn’t know the answer to and suggested they look it up later. The session with the Year 6 class, one boy asked the very first question: “How big is Uranus?” – setting off a lot of giggling. I quickly said something factual about the planet and then moved on. Only afterwards did I realise I should have answered: “Not big enough to be sat-urn. Next question.”

After the group sessions (and the recess break) I had Science Club with my 13 students who I’ve been working with all year. As this was our final session, I didn’t have time to run another experiment, so we just sat and had a discussion about what we learnt this year, about science in general, about what sort of jobs you can get in science, and then I let them ask any questions they had, and tried to answer those. Here’s the whiteboard we were using, at the end of the session:

Science Club board

I cam home mid-afternoon. I went out on the balcony to assess the leftover mess from the chilli plant blowing over. And then, as I was standing out there, another gust of wind blew over the basil plant I’m growing for use in cooking! Soil went everywhere, and because the balcony door was open, including inside, on the carpet, and even on the dining table!

Today was really windy. I had a late lunch out, after finishing Science Club, sitting by the beach, and the wind was blowing wildly, making trees sway violently, generating huge whitecaps on the ocean. It was really awful conditions. Oh, and as I was driving to and from the school, I passed some of those areas where the power lines were still down today, 6 days after the storm last week. A friend of mine had no power from last Tuesday to Sunday night – 5 full days.

Anyway, with the wind still blowing strongly, I just quickly swept up the largest piles of soil, righted the basil, and placed the plants in sheltered positions against a wall, so hopefully they won’t blow over again.

I also decided not to take Scully out to the dog park where we meet other people and dogs, as it’s down by the water and it gets windy there even on calmer days, so today would be intolerable. Instead I took her downstairs, intending to cross the road to the nearby park which is a lot more sheltered, and let her just chase a ball for a while. As we were coming out of our property, Scully pulled up lame, favouring a rear leg. I thought she must have a burr or something stuck on her paw, as she was trying to get something off. I grabbed her leg and brushed the base of the paw, finding a sticky lump, which I pulled off…

It was a bee.

Next thing I knew, I had a shooting pain in my thumb. It stung me right on the pad of my thumb. I’ve never been stung by a bee before, so my lifetime record is now trashed. The bee fell to the ground, but the sting was stuck in my thumb. I scraped it out with a fingernail. It hurt a lot – but honestly nowhere near the pain I got from a jack jumper ant sting a couple of years ago. Given a choice, I’d take the bee sting any day. Anyway, I aborted the park trip and went back inside with Scully to wash the sting area and apply ice for a while.

Ten minutes later I was fine and resumed taking Scully out for exercise. (The jack jumper ant sting throbbed for months.) We played in the park a while. Then, just as we were turning to head home, a huge gust of wind blew into my face from the south, bringing a strong smell of smoke.

The bushfires around Sydney have been burning for a couple of weeks now, and every few days the winds bring the smoke into the city. Some days it’s been really terrible – horrible choking smoke everywhere. Today had been okay, up until that moment. As we walked home, I could see clouds of smoke, made orange by the late sun, wafting across the sky.

Here’s a photo someone posted to reddit as the smoke drifted in: [photo]

And another photo from nearby shortly afterwards: [photo]

In the endless struggle of Man versus Nature, today Nature won.

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Science assembly presentation

Today was the presentation by my Science Club kids at their school assembly, in front of the whole school. (I wrote about the preparation for this here.) Since it was at 2 o’clock, I decided to head out and get some lunch somewhere nearby, and then head to the school after that.

I went to a Spanish tapas place at Dee Why, a beach suburb. Here’s the view from my lunch table:

Lunch view

The meal was pretty good! I’ll have to come back some time with my wife and Scully. After eating, I went for a brief walk along the beach:

Dee Why Beach

And then back to the ocean pool at the southern end of the beach:

Dee Why Baths

There were a lot of people out for a Thursday lunchtime, enjoying the warm but not-too-hot late spring day. There’s still a bit of bushfire smoke in the air, which you can see in the photos, but it didn’t smell particularly bad today. Far out to see I saw a giant yacht on the horizon (a racing yacht, not a motor yacht). It must be out there with the crew practising for the Sydney to Hobart Yacht Race, which begins on Boxing Day.

The extra wide lens on my new phone camera is pretty cool:

November day at Dee Why

I drove over to the school and checked in with the science coordinator. She said that the preparation I’d done, writing a script for the kids to read along with the slides, couldn’t be found because the girl I’d written it with had been away for a week and hadn’t told anyone where she saved the file! So the other kids had had to write their own script from scratch!

At the school hall, there were a couple of rows of seats in the back for parents, although there were only a handful there. A woman came up to me and introduced herself as Belle’s mother, Belle being one of the girls in the Science Club. She thanked me for volunteering my time at the school and helping out with the kids’ science education, and said Belle was really keen on science. I said I enjoyed doing it, and especially showing the kids that if they like science then it’s possible to have a career doing it. We chatted for a bit before the kids filed into the hall.

There was some preliminary with kids getting weekly merit awards, and then the Science Club kids gave their presentation using the slides I’d prepared. Their script was a little bit wrong in places, but I don’t think it mattered much. It was great to see the kids on stage talking about all the experiments we’ve done this year.

Afterwards I chatted some more with Belle’s parents, until the bell rang and classes were dismissed, and Belle arrived. Her mother took a photo of me with Belle! Although I didn’t really do much at the school today, it was good seeing the presentation, and meeting Belle’s parents.

Then I had to drive home… On the drive out there, I’d seen just how much devastation there was from the storm on Tuesday. One road I drove along had trees down every hundred metres or so, in some cases with power lines still down and safety tape around the site. Some of these had power company workers busy clearing the trees and restoring the power lines, but others were completely unattended. Clearly they don’t have enough workers to get to all of the downed lines at once. I heard on the radio news while driving that the job is so large that they expect up to 20,000 homes to remain without power over the weekend. It was incredible seeing so many destroyed trees.

At home I’ve been working on a new 100 Proofs that the Earth is a Globe post, but it won’t be ready today – hopefully tomorrow.

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Fire day

The main thing about today was not anything I did, but the weather and the resulting fires across the Eastern parts of Australia. We’ve had out-of-control bushfires burning in various parts of New South Wales and Queensland since the weekend, and today’s weather was very hot and windy. The combination resulted in declarations of (a) total fire bans across all of NSW and Queensland, (b) “catastrophic” fire conditions in the Sydney and surrounding regions – the first time this warning level has ever been issued for Sydney, and (c) an official state of emergency in NSW from today, for the next seven days.

Over the past few days, several hundred homes have been destroyed by fire, and a handful of people have been killed by the fires. We expected the worst today, as temperature rose to 37°C in Sydney, and hotter in some rural areas, with very low humidity and high winds. Throughout the day as the temperature climbed, I kept up with the news, hoping not to hear of further tragedies.

While this was happening, I spent the morning back at the school I went to yesterday, working with a couple of the kids in the Science Club, to prepare a short slideshow presentation of the work we’ve been doing all year. The older kids in the Science Club are going to present the experiments we’ve been doing to the whole school at an assembly in a couple of weeks. They have a 15 minute slot, so I made sure to keep things tight, and helped them write a script to read from.

I was home around lunch time, and then began work on getting a result from our solar shadow measuring experiment, that the kids have been working on since May – recording the length of a shadow each day as the sun moves.

Later I went out with my wife and Scully to the pet shop, for some exercise, since it was a much cooler option that going to the park. We walked over to the hardware store as well, and a couple of other places nearby to buy a few odds and ends. Scully enjoys going to the pet shop, as there are so many interesting things to smell. But she was getting restless again early this evening, so I braved the heat and took her to the nearest park to chase a ball around for a while until she got exhausted. While we did this, I could see the smoke from the bushfires around Sydney drifting across the sky.

Scully and the bushfire smoke

(This photo was walking home, not at the park.)

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School science visit

Today was my visit to the primary school where I talk to the kids about science stuff. I had three separate session with kindergarten, Year 1, and Year 2. As mentioned on Saturday, I presented a talk on dinosaurs for the K and 1 kids. I included a bunch of photos of fossils with feathers, and showed them what feathered dinosaurs look like. The conclusion was that only some of the dinosaurs died out a long time ago, but some of them – the birds – never died out at all, and are still around us today. They really enjoyed it, so that was good.

With the Year 2 class I did a general Q&A. Some of the questions they asked included:

  • Where did the Earth’s water come from?
  • Why did the dinosaurs die out?
  • Where did humans come from?
  • Why isn’t Pluto a planet any more?
  • How do you make a black hole?
  • Does the Earth run on coal? – I talked a bit about what coal is, and how it’s used to make electricity, and how it adds carbon dioxide to the atmosphere, and how this is a bad thing because it’s causing climate change, but how hard it is to stop using it because people need the electricity.
  • How do potions work? – This was fun. I talked a little bit about how potions are fictional and don’t really work like in books and movies, and also a bit about alchemy and how alchemists used to believe they could make magical potions. By mixing things together and learning how they worked, they actually invented the science of chemistry instead.

Besides these three large groups, I also had Science Club with the group of 13 students I’ve been working with all year. It’s really quite a strange thing to be left in charge of 13 kids aged 7 to 10, with no other supervision, and be allowed to do science experiments with them (not on them!). Today I brewed up a pH indicator liquid by mixing hot water and shredded red cabbage. Within half an hour (during which I went over the results of our previous laser experiment), we had a rich purple liquid strained off. I gave each child a plastic cup and one of the chemicals I’d brought in. Then we added the cabbage liquid to each and watched them change colours:

pH experiment

pH experiment

From left to right around the table, the kids had: baking soda, soda water, white wine, bleach, apple juice, cream of tartar, lemonade (i.e. Sprite/7-Up for the Americans), vinegar, lemon juice, and ammonia solution. The bleach and ammonia I gave to the oldest kids, and made them wear rubber gloves for safety. And you can see the different colours they produced. Here’s a shot with them arranged in order of pH:

pH experiment

After establishing a sequence of colours for the chemicals, we tried mixing some of them. Adding baking soda to the vinegar made it (1) fizz up, (2) change colour, becoming a deep blue-purple. We mixed a few other things together, and the kids tried to predict the resulting colours (without much success). We established that mixing acids and bases tends to neutralise the result, making it closer to the original neutral purple colour. I made absolutely sure we didn’t mix the ammonia and bleach – I didn’t want to be generating chlorine gas!

This pretty much took up my whole day, as it took a while to drive home in the late afternoon traffic. And I was exhausted! I don’t know how school teachers do this every single day!

New content today:

Science Saturday

Besides the usual bathroom cleaning, I dedicated much of today to Science! I finished writing that 100 Proofs article I’ve been mentioning.

And I planned out what I’ll be doing with the school children on my next STEM Professionals in Schools visit on Monday. I wanted to do a Q&A session with all the classes, because it’s minimal preparation for me, but my contact said the kindergarten and Year 1 teachers requested me to do a presentation, because their kids are too young to be able to come up with sensible and meaningful questions. [It’s true – last time they got fixated on asking me “how many X are there?”, for X=(cats, animals, fish, bones, trees, etc).] SO I went through my old slides and found one I did on dinosaurs 5 years ago – so none of the younger kids will have seen that one. I refreshed myself on what was in the slides so I can talk about it on Monday.

And for Science Club I planned a new experiment. We’re going to make pH indicator using red cabbage, and then test various household chemicals. The usual suspects like lemon juice, vinegar, baking soda, etc. Which meant I had to draw up a shopping list. I’ll have to go shopping tomorrow for everything I need.

Oh, and I spent a bunch of time making tomorrow night’s Darths & Droids strip, following the writing session yesterday.

And now, it’s late… time for bed!

New content today:

Summery Friday

It was hot today: 33.5°C in Sydney. Summer has definitely arrived early. Not only is it unusually warm, but much of south-east Australia is in the worst drought in recorded history. Several towns are in imminent danger of their water supplies running completely dry. Dubbo, a large regional town announced upgrading to Level 4 water restrictions this week, which makes showers longer than 5 minutes illegal and all watering of lawns illegal. Sydney is currently on Level 1 water restrictions but it probably won’t be long before we start climbing the levels too.

Another big fear is bushfires. As the weather heats up towards summer, the dry vegetation all over south-eastern Australia is going to be at great risk. It’s been a couple of decades since the last disastrous level fires with tens of lives lost, but everyone is nervous about this summer.

I stayed in out of the heat today and tended to a stack of odd jobs I had piled up – literally – on my desk. I sorted through the pile of papers and paid some bills, filed some documents, organised things needed for my upcoming trip to Germany, and collated data collected from the laser experiment during my last school science visit. I calculated the wavelengths of the lasers we used from the interference patterns the kids traced and put it into a slideshow to show them on my next visit. It turned out that their sketching skills were not great, with some individual wavelengths being out by almost 100 nanometres, but luckily the averages of three measurements made with different slit configurations turned out to be within 9 nm (or under 2%) in each case. A good result, if honestly more by luck than careful measurement!

For dinner tonight my wife and I went to a French crepe place that we discovered recently. It’s run by four French immigrants who loved everything about Australia, except for the fact that they couldn’t find good crepes anywhere, so they decided to start their own restaurant. Both the savoury galettes and dessert crepes are really good, washed down with imported French cider. And outdoor seating, so Scully is allowed to sit with us.

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