Biology in the classroom

Recently in year 8 we have been studying cells. While studying cells students have learned about all the tiny ‘organelles’ (little organs) inside the cell. An organelle of particular importance is the chloroplast. Chloroplasts absorb light and are the part of plant cells where photosynthesis occurs.

Photosynthesis is a vital chemical reaction that converts and stores energy from the sun into sugar (glucose). The reaction also removes Carbon Dioxide from the atmosphere and gives off Oxygen. The removal of Carbon Dioxide is vital for a healthy atmosphere – currently our society’s addiction to burning fossil fuels is building up significant levels of Carbon Dioxide in the atmosphere, which is slowly causing the Earth to get warmer. The addition of Oxygen is also vital as all living things (including plants) use Oxygen to extract energy stored in sugars through the chemical reaction called respiration (which some people refer to as the reverse reaction to photosynthesis).

It is important to remember that plant’s are living things as well. Viewing chloroplasts with a microscope is an easy way to remind students of this fact. One of the criteria used by year 8 to determine if something is living or not is whether it responds to changes in the environment. Chloroplasts are able to directly respond to changes in the amount of light available. In low light they have been seen to spread out, increasing their surface area to absorb the most light possible. In intense light, like the focussed light from the microscope lamp, the chloroplasts attempt to align themselves ‘edge on’ to the light and continually move seeking shelter behind other chloroplasts.

The video below was taken during class using a mobile phone camera held up just in front of the microscope lens (very fiddly, sorry for the unstable video!). If you’re able to see past the shaky filming you will see this amazing stimulus-response reaction from the chloroplast and see conclusive evidence that plants are living!

(if you’re struggling with the shaky film, skip forward to 0:46 seconds).

Or check out this more stable version from mantismundi user on youtube:

Science Club is back for 2013!

We had a lot of fun this week playing with dry ice. Dry ice is the solid form of Carbon Dioxide (the colourless gas that we breathe out). Dry ice is special because unlike normal ice it doesn’t melt (and leave a puddle) instead it sublimates – it changes straight into a gas without becoming a liquid. It’s also special because it is very cold, -78.5 degrees Celsius. There’s a greater temperature difference between your hand and dry ice than your hand and boiling hot water! Dry ice is very dangerous to our bodies, it can freeze the water in our cells and the sweat on our skin (sometimes sticking to you just like when you lick a frozen ice cube or ice block and your tongue sticks to it) creating a ‘freeze’ burn or even frostbite that is potentially much worse than a regular burn.

As dry ice sublimates into a gas very quickly there are several very cool effects that it produces. Firstly, when you add dry ice to water the sublimation occurs much faster. The Carbon Dioxide gas that is produced is very cold – cold enough to cause most of the water vapour in the air condensate. The effect is that we very literally make a small cloud. However, the cloud only forms where the cool Carbon Dioxide gas is flowing. Another unusual property Carbon Dioxide has is that it is denser than air, so it’s a gas that literally ‘sinks’ in our atmosphere. This means that the cloud we make also sinks in the air and creeps along the ground.

Unfortunately I forgot my camera on the day and don’t have any new photos to share, but here’s the key effect we were experimenting with:

(A previous attempt at creating a dry ice tornado by Mr Wright and myself)

The end product we hope to use in the upcoming Wizard of Oz musical:

You can see the rest (including our big explosion) in last year’s post.

Sleek Geeks Eureka Prize

Check out the below announcement from


The University of Sydney Sleek Geeks Science Eureka Prize will again be offered in 2013 to primary and high school students. The competition encourages students with a passion for science and for communicating ideas to tell a scientific story via a short video piece, cultivating the next generation of Dr Karls and Adam Spencers!
Recognised by teachers for its relevance to the primary and high school curriculum, the competition has become a staple activity in the classrooms of many schools across Australia. Every year the judges are overwhelmed by the creativity and quality of entries, and the Faculty of Science wishes to congratulate all students who participate in the competition.
The 2012 competition proved to be another huge success with over 200 video entries received from schools around the country. Every year the judges are overwhelmed by the creativity and quality of entries, and the Faculty of Science wishes to congratulate all students who participated in the competition. We look forward to another year of science videos!
ENTRIES OPEN: Friday 1 February 2013

ENTRIES CLOSE: Friday 26 April 2013
Primary school category: conditions of entry and online entry form

Secondary school category: conditions of entry and online entry form

What’s involved?

The idea is to communicate a scientific concept(s) in a way that is accessible and entertaining to the public while painlessly increasing their science knowledge or, as the Sleek Geeks like to say, “learn without noticing”. All you need is a handycam – it’s about the content and creativity. For inspiration check out the top 2012 entries on the ABC Science website.
Entries are to take the form of a one to three minute video piece and a 50-word description of the video content. Entries may be produced by an individual student, or a group of up to six students. Read the Judges Hints and Tips on producing an award-winning short film!

Prize breakdown for the 2013 competition

High School Prize 1st – $4,000 plus a $500 book voucher from Abbey’s Bookshop, Sydney 2nd – $2,000 3rd – $1,000
Primary School Prize 1st – $2,000 plus a $500 book voucher from Abbey’s Bookshop, Sydney Runner up – $1000
The prize is sponsored by the Faculty of Science at the University of Sydney, with additional support from Abbey’s Bookshop, Sydney and Microsoft.


For more information about the University of Sydney Sleek Geeks Science Eureka Prize, please email

Send me an email (or comment below) if you’re interested in having a go and I’m happy to help you piece together your ideas and make it happen!

You can see the winning entries from previous years here:

This week in Australian Science! (25/3/12)

Check these new findings out from Australian researchers:

Australian scientists found cicada’s wings can destroy bacteria, earthquakes deposit gold in the Earth and nerve-protecting cells could play a role in Alzheimer’s disease. Read more:

→ Cicada’s wings shred bacteria:
→ Insulating cells can be added throughout our lives:
→ There is only one giant squid species:
→ Earthquakes put gold in the soil:

(Content from the facebook group for ScienceAlert)

This Week In Science

Amazing things are happening in science at the moment. Check out the newest discoveries from just the past week!

Follow the links for more information:
Bee venom and HIV:
Breath test for cancer:
3D printed skull:
Child cured of HIV:
Space invader shaped galaxy:

This article content and image is from ‘Science is Awesome‘ facebook group (post date 12/3/13).

Stellar Evolution – updated theories

“This graphic gives a summary of our best current understanding of the evolution of stars, showing their birth, middle age and eventual demise. The lowest mass stars are shown at the bottom and the highest mass stars at the top. The very top line is a new addition, compelled by the detection of SN 2006gy — one of the brightest stellar explosions ever recorded — that describes the evolution of the most massive stars in the universe. Observational evidence for the special type of explosion shown here — which is incredibly bright and obliterates the star rather than producing a black hole — was lacking until SN 2006gy was found.”

Image and text via the SETI Institute.

Check out the animation for SN 2006gy:

This star is thought to be 130-250 times the size of our sun and while the light from the explosion was seen in 2006, the star is located so far away that the explosion actually occurred 238 million years ago and only a few years ago managed to reach Earth.