QCAT science test Qld

[pkij]

We are doing our QCAT test next week. Has anyone done this yet? I am trying this out at the moment and the set up they have given seems a bit dodgy. The hydrometer I have prepared as shown sinks straight away to the bottom of the test tube, it just floats without the nails in the straw. Blu tac does not seem to stick very well to the straw.

If anyone has done this with success please please let me know if there is some modification that helps make it work!

[Phoenix]

I set the QCAT pracs up for our teacher a couple of weeks ago and it apparently worked quite well.

To make my hydrometers I bought new blutack (I find its a little bit more sticky than stuff thats been used before or left out) and used a piece that was about the size of a pea. The nails I used were small iron nails about 1.5cm long (the first nail I tried was longer and too heavy and it made the straw sink). I stuck the nail head into the blutack and then slid it up into the straw and molded the blue tack around the edges to make it water tight.
It bobbed quite happily in the middle of the test tube of distilled water.
Try using a differnt sized nail or alternative weight until you get the straw hovering between sinking and floating.

Hope this helps
Cheers
Kelli

[smiley]

I spent an amount of time yesterday trying to make this ridiculous straw hydrometer work!

Yes, I can make it float happily in water, although marking the exact spot where it floats is a bit arbitrary, since you have to measure on the outside of the test tube, taking the meniscus into account etc etc! But making it differentiate between %solutions of sugar is ridiculous. I can't get an effective difference between 10% & 15%. If I can't do it, how will the kids??

Feeling totally frustrated here, and NOT very smiley at all.

Any ideas, tips you other Qld labbies?

[pkij]

We completed QCAT last week, now I wonder if anyone tried it out before it was set for QCAT? It was difficult for me so for Year 9 students?????
I made the hydrometers ok, thanks for the hints Kelli (Phoenix).
Making the mark on the straw was difficult and very inaccurate, we had results ranging from 2 to 8 teaspoons of sugar compared to the soft drink provided (it should have been 10 - 11 teaspoons according to our sample.
Oh well its done now and I guess they are not marked on the practical, but on their scientific "interpretation", still it would have been more relevant if they were able to get closer and more consistent results.
It would be interesting to see how other schools went (from a Labbies point of view!)

[Kathy]

Yes I wondered too if it had been tested before being put into the QCAT book. Is it written by a science teacher? I would hope not. I tried it and the Year 9 teachers all had a go before their classes did it. Between the 7 of us we had variations of between 2 and 14 teaspoons of sugar. Silly, scientifically inaccurate experiment.

[fibreweb]

For us in other states, can you tell us what they were required to do?

I'd never heard of the QCAT before this.

Wendy

[smiley]

OK. Kids have to make a hydrometer, using a straw, bluetac, and a couple of nails. They float it in water and mark off the spot on the straw, at the level of the meniscus.

Then they float it in a sample of flat soft drink (i.e. no bubbles adding to the flotation). Then they make sugar solutions using 1, then 2, then 3, etc teaspoons of sugar, and test the density of the solution each time. The aim is to determine how many teaspoons of sugar are in a can of soft drink.

Sounds simple, right? Wrong!

Today, I am going to try it using a diabetes urinoscopy hydrometer, (an actual piece of laboratory equipment)and see if I can get results worth a damn.

Apparently, in other schools, kids had to write their report based on negative results - "Why this didn't work". Pretty mongrel sort of a thing to do to Yr9's I reckon. Whether they are bright and science-minded, or totally not interested, I think it is going to be an exercise in universal frustration, starting with ME!

[pkij]

QCAT is Queensland Comparable Assessment Tasks. According to the blurb they are designed to "provide evidence of what students know, understand and can do in relation to a selection of Essential Learnings for english, mathematics and science in Years 4, 6 and 9 and to the standards".
For science they do a practical and then complete a workbook, they receive a mark somewhere down the track. I guess its a standard for all Year 9's to see how they perform in the subject areas.
Sounds great in theory but the practical does not achieve much if they have to discuss "negative" results when the students are meant to be looking at sugar in out diets.
Wonder what they will come up with next year?, think they need to give to some Labbies to try out first!

[RosalieM]

I reckon it would be worth writing to the board of studies or whoever designed the tests to tell them the rediculousness of it and also make suggestions for the future while you're at it! Poor kids...

[Narelle01]

Sounds a little like the NAPLAN that is ow done Australia wide in 3,5,7,9.....but naplan doesn't cover science.

NSW started it with basic skills - then went national...to NAPLAN

[Labbie]

Is it ESSA that covers Science. I guess we will all be the same next year, with the National Curriculum coming in. But I have no idea who is doing the National Curriculum and its tests. Does anyone know?????????????????

[smiley]

To all my QLD colleagues: I had a modicum of success with "Wendys" straws (the ones they put in thickshakes), and 3g of lead shot instead of nails. The thought was to the fatter the straw the more upthrust it has in a TT of solution. I also cut it off to about 14cm. It produces a perceptible difference, but only just. The results tend to flatten out after about 8 teaspoons per 375mL.

Variables are: weight of bluetac, the definition of a "teaspoon" i.e. it's not an accurate measure, because it could be heaped or flatter, so the quantity changes each time you lift "one teaspoon" out of a quantity of sugar, the marking pen adds height to the line you just marked - the lines on the commercial hydrometer are very fine and only 1mm apart, and probably room temperature (it's nearly 30 degrees here at my desk today, according to my thermometer, which I believe).

I also conducted this test with a commercial hydrometer, as mentioned last post, and it worked well, but the results aren't entirely linear. I think if a hydrometer used on a diabetic patient was digital, it would be making alarm noises once it got to more than 10% sugar. The patient might be in a coma!

My teachers intend to lodge a complaint with QSA about setting an impossible task. One teacher said it sounded very much like they got a prac out of a book without testing its viability. Perhaps you could enjoin your teachers to have their say too!

[nickyw]

Smiley my HOD is going to complain about it too. Just not scientific enough. How can you teach students to be accurate when they have to used 3rd rate equipment. We had such a variation in results, but how could there be a right or wrong answer????

Keep it simple yes.....but keep it scientific as well using real scientific equipment.

(Maybe a boost in funds as well so we can pay for said equipment)

[smiley]

Right on for the boost in funds!

I think the more voices that can be added to the protest, the better. I think the very fact that adults had to muck about and tweak the experiment makes it out of the range of the average Yr9 student.

Have a great break!