Today, we are going to explore a website where a number of scientific experiments have been setup already, all a user has to do is to change the settings and items to see the cause and effect relationship. This is phet.colorado.edu, a University of Colorado website, which has a large number of beautifully rendered interactive illustrations. It contains everything from physics and biology to projects such as lunar space Lander and Rutherford experiment.

The depth and breadth of topic coverage means one can find nearly all the concepts taught in contemporary science books translated into simulations with considerable user control. For example, under projectile motion simulation, users can choose between a golf-ball or a tank-shell (among others) and set up a hole or target. To test the projectile throw, set up the angle, initial speed and mass and press the Fire button.

These parameters can be changed; the resulting distance, time and height are shown in addition to tracing the path of flight and place of impact on the ground. Similarly, there's an optics simulation where user can change the lens parameters and move items such as light source and see how it is projected onto a screen.

It almost feels like performing these adjustments right on an experiment desk as changes take place in real-time without any setup and playback requirement as is the case with other dedicated simulators.

On the informative side, each simulation has a learning goal attached to it along with teaching ideas containing sample questionnaire based on selected simulation. What makes this site different from others is the range of topics covered. Apart from the usual ones such as gas, gravity and electricity, it has got detailed controllable simulations on topics such as DNA, nuclear reactions, alpha decay, green-house effect and MRI (a medical imaging machine), etc.

Some of these are detailed enough where hours can be spent understanding the impact of changing simulation scenario to grasp the concepts. For instance, there's a Pendulum Lab offering controls like setting up mass, length of string, friction, gravity and then allowing the swing using mouse-drag motion at desired angle. Once the pendulum starts swinging, check the 'show velocity' and 'show acceleration' options along with turning on energy bars. These factors are added graphically and change continuously along with the swinging motion. One can clearly see these factors such as which forces act in which direction at what point in time with what intensity — something that cannot be observed even in a real experiment setup.

Simulations are categorised by subjects, such as math, earth science, etc., or it can be broken up grade-wise by using the Grade Level link. Here, categories include elementary, middle or high-school and university. An interesting link is 'For Teachers' where subject-wise activities can be searched and downloaded. Students who want to be a step ahead and prepare for quizzes can actually take help from here.

Note that if a simulation does not run in browser due to a missing plug-in, either install it or use the download button to download simulation's JAR file and then run it from command line using

java -jar <downloaded-file-name.jar>

Happy simulated learning!