Author: Lensyl Urbano

Quick Reference: Adding Fractions with Different Denominators

To add fractions with different denominators you just need to multiply each fraction to get the same denominator:

Take:
\frac{3}{5} + \frac{5}{9}

The easiest common denominator will be the product of both denominators ( 5 × 9 = 45 ). So multiply each fraction.

\frac{3}{5}\times\frac{9}{9} + \frac{5}{9} \times\frac{5}{5}

Notice that you’re really multiplying each fraction by 1 (since 9/9 = 1 and 5/5 = 1) and anything multiplied by one remains the same number. So you’re not changing the value of the fraction, just how it looks.

Now doing the multiplication gives:
\frac{3}{5}\times\frac{9}{9} + \frac{5}{9} \times\frac{5}{5} = \frac{27}{45} + \frac{25}{45}

Which we can add because we now have a common denominator:
\frac{27}{45} + \frac{25}{45} = \frac{52}{45}

And simplify to give a mixed number:
\frac{52}{45} = 1\frac{7}{45}

Resonance Frequencies: MythBusters investigate Tesla’s Earthquake Machine

The whole episode is worth watching, but this little section (at 10:52) of MythBusters’ attempt to build an earthquake machine there demonstrate the resonance frequency in a water tank provides a nice visualization.

Rethinking Classrooms with Pedagogy in Mind

OnlineUniversities.com has compiled an interesting list of ways what we’ve learned from neuroscience is being used to rethink school and the classroom.

From 9 Signs That Neuroscience Has Entered the Classroom via OnlineUniversities.com.

Much of the list consists of simpler, practical things that are straightforward (if not easy) to implement: like starting school later (for the adolescents), emphasizing more group work, and stressing the importance of the emotion (positive affect).

But the article also points out some of the newer technology based approaches, such as interactive “cognitive tutoring”.

It’s a useful introductory reference.

↬ K.Cole.

Landing the Mars Rover: 7 Minutes of Terror

NASA gets dramatic. But the drama is oh so appropriate when you see what they have to do to land a rover on Mars. There are so many steps to the landing — heat shields, atmospheric friction, parachute, rockets — that it’ll be amazing if it works, and the video is a wonderful “strike the imagination” introduction to the physics of forces.