Posts Tagged ‘Science education’

The effect of graded homework assignments on other grades

Friday, May 4th, 2012

Here’s a comparison I did of the results of using graded homework assignments in a freshman-level chemistry class.  The classes compared all had homework assignments given each week, but only some of them had assignments that were taken up, graded, and counted directly towards the final course grade.

Change in average test scores

As you can see, there was a nearly a letter grade improvement in scores on the first test, compared to classes that didn’t have the graded assignments.  There was an improvement on the second test as well, though it’s much more modest than the improvement on the first test.  So the graded assignments appear to help students start off the course on a better footing than they would have otherwise.

However, the scores for the third and fourth tests are nearly half a letter grade lower than for the classes without the graded assignments.  What’s the cause of this drop in performance?  A few possibilities:

  • Attrition may explain some of the falloff.  Students who started off more poorly in the classes without the graded assignments are more likely to withdraw from the course earlier – leaving a greater percentage of higher-performing students behind for the last two test.  (The latest a student is allowed to withdraw from a course is shortly after the third test.)
  • Student participation in the graded assignments dropped somewhat as the semester progressed.  More students skipped turning in homework before the third and fourth tests compared to the first and second.
  • Students are more likely later in the semester to copy their assignments from other students of from tutors in the school’s tutoring center – depriving them of any benefit they might have gotten from doing the assignment.

For the final exam, the students in the graded assignments classes showed a small improvement over the others.

Since these classes are small sections as opposed to large auditorium classes, here’s a look at the median change in test scores for the same set of students.

Change in median test scores

The median scores follow roughly the same trends as the averages do – with better performance on the first two tests and poorer performance on the later tests.  Interestingly, the median final exam scores for the students with graded assignments was slightly lower than the median final exam score for students without the graded assignments.

Happy birthday, Robert Bunsen!

Thursday, March 31st, 2011

If you’ve visited Google today, you might have noticed that their logo looks a little strange.

That’s because it’s the 200th birthday of Robert Bunsen

Born in Gottingen, Germany, on March 31 1811, Robert Wilhelm Eberhard Bunsen was a prominent chemist in his day who discovered the elements caesium and rubidium and developed the Bunsen cell battery.

But he is best remembered for the distinctive gas burner he developed with his laboratory assistant Peter Desaga in 1854 and 1855 to study the colour spectrum of different heated elements.

…. the man behind the Bunsen burner!

Fun with non-Newtonian fluids

Friday, June 19th, 2009

Terra Sig links to a neat demonstration of the properties of non-Newtonial fluids.  Or, more specifically, the properties of shear-thickening fluids – fluids whose viscosity increases when deformed.  Put simply, these are liquids that act more like solids when you try to change their shape too quickly.

The test fluid for the demonstration?  Silly Putty.  Fifty pounds of it.  Dropped off of a building.  Neat, eh?

I do have a suggestion for next year’s demonstration, though.  Drop the fifty pound silly putty block from the building into a large vat of corn starch in water.

Why corn starch and water?  Corn starch/water mixtures are also shear-thickening fluids.

Which shear-thickening fluid would reign supreme?  Tune in next time to find out!

Which shear-thickening fluid would reign supreme? Tune in next time to find out!

It’d be an Iron Chef of non-Newtonian fluids!

Debate #3: The Final Beat-Down

Thursday, October 16th, 2008

I didn’t have the opportunity to record my thoughts on the debate as it happened, but here are some thoughts on the final Presidential debate.  I’ll probably post some more as I get time.

Here’s a link to the debate transcript from CNN.

Let’s talk about education.  Here’s John McCain talking about what he will do about science education. He’ll cut spending on things that are useful to science education as wasteful “pork”.  Things like planetariums.

Sen. Obama has asked for nearly $1 billion in pork-barrel earmark projects… including $3 million for an overhead projector in a planetarium in his hometown. That’s not the way we cut — we’ll cut out all the pork.

I’m not sure who McCain thinks this tidbit – which he’s mentioned in the past two debates – is supposed to impress.  I do know that he’s probably managed to alienate any science educator in the country who is paying attention.  For those of you who weren’t – John McCain thinks science outreach is wasteful “pork”, and he will eliminate it.

And while we’re on the subject of “pork”, Obama happened to bring up an important point:

Now, Sen. McCain talks a lot about earmarks. That’s one of the
centerpieces of his campaign.

Earmarks account for 0.5 percent of the total federal budget.

So McCain’s campaign is built on obsessing over half a percent of the budget?  No wonder Republicans are so bad at controlling the national debt.  They can’t see the forest for the trees.

Brunswick Stew-pid

Thursday, September 18th, 2008

Looks like our northern neighbor is affected by the same disease that Upstate SC has:

the Brunswick County school board began discussions on teaching creationism alongside evolution – something all four board members present showed a strong interest in. The talk began after Joel Fanti, a parent and graduate of the school system, told the board that he considered it a problem to teach evolution as a fact and that science teachers should include creationism in the curriculum, as well.The audience applauded.

… a case of The Stupid.  At this point, it seems that the state will squash this little Stupid outbreak.  The higher-ups in the NC school system recall the Dover trial.  This, after all, would be a more blatant attempt than the one in Dover to replace science with religion in the science classroom.  A lawsuit would almost certainly follow.

One more disturbing point:

Teachers have alternative assignments for students whose parents have objections about evolution, but students are still assessed on the topic in state tests

Lovely.  Parents can opt their kids out of biology, but teachers are still held responsible for students whose parents won’t allow them to learn?