Monthly Archives: February 2011

Programme for International Student Assessment

The Programme for International Student Assessment (PISA) study is conducted every three years by the Organisation for Economic Cooperation and Development (OECD). The OECD is a group of thirty-four countries with “advanced economies”, which basically translates to “club for rich countries”.

The PISA study gives 470 000 15 year-olds a test in literacy, numeracy and science and has just released the results of the 2009 study. The UK comes out above average in science and reading, but below average in mathematics.

I was quite interested in the correlation between between scores:

  • Between science and mathematics was 97.1%
  • Between science and reading was 98.1%
  • Between reading and mathematics was 94.8%

I had expected the highest degree of correlation to be between science and mathematics, but that is probably a physicist’s bias, as maths is such an important part of physics.

Penrose tiling

Sir Roger Penrose is a mathematical physicist best known for his work on theories of general relativity and cosmology. He won the Wolf Prize in 1988 with Stephen Hawking for his work on singularities and black holes; the Institute of Physics’s Paul Dirac Medal and Prize in 1989; and the Royal Society’s Copley Medal in 2008 for “his beautiful and original insights into many areas of mathematics and mathematical physics.”

He is also the inventor of Penrose Tiling, a unique tiling pattern with five-fold symmetry, so I was delighted to discover this building as part of the Greenwich Peninsula complex outside the O2 Millenium Dome.

Almost the entire surface of the Ravensbourne College of Design and Communication building is covered with a Penrose-inspired pattern. Penrose previously sued Kleenex for using his tiling pattern on their quilted toilet paper, but I imagine that Ravensbourne’s architects, Foreign Office, checked with him first.

Time on the Moon

I was surprised to find that the amount of time spent on the Moon by Neil Armstrong and “Buzz” Aldrin on the Apollo 11 mission was really quite small when compared with the time spent by astronauts on subsequent Apollo missions.

Only 12 people (all men, unfortunately) have ever set foot on the Moon. The person to spend the most time on the Moon is Gene Cernan, the commander of the Apollo 17 mission. He left the Apollo lander before the Apollo 17 Lunar Module pilot, NASA geologist Harrison Schmitt, and re-entered the lander after Schmitt. He is therefore also the last person to set foot on the Moon, all the way back in 1972.

Gene Cernan cruising the lunar surface in the lunar rover

Cernan also co-holds (with Thomas Stafford and John Young) the record for the fastest speed achieved by a human being, as the Apollo 10 probe on which he was a passenger reached a speed of 11.1 kilometres per second (24 790 mph) on its return to Earth after orbiting the Moon. The Apollo 10 Command Module is now on display at the Science Museum in London.

Datalogging the lesson

My department recently bought some nifty portable dataloggers. I decided to test one out during my last two periods with 5PHC by measuring the volume of sound in the room during the lesson’s ninety minute duration.

Because the volume of sound spans many orders of magnitude it’s not really possible to measure all possible volumes accurately. I used two different sensors: one measuring from 30dB to 70dB and one measuring from 50dB to 90dB. When a measurement was picked up by both devices I used the average value.

The original data is very noisy, partially because the sampling was done five times per second and partially because the volume of sound produced by twenty-one fifteen and sixteen year-olds can vary very quickly.

I averaged the data over a moving thirty second period to produce a more useful graph:

The average volume during the whole lesson was 56.9dBA. The “A” in “dBA” indicates that the sound pressure level sensor I used was using A-weighting that attempts to reproduce the human ear’s response to sound.

You can see gradual increases in volume punctuated by shouts of “QUIET!” that cause the volume to drop very suddenly.