PhET/C2/Graphing-Lines/English-timed

Time	Narration
00:01	Welcome to this tutorial on Graphing Lines simulation.
00:05	In this tutorial, we will demonstrate, Graphing Lines, an interactive PhET simulation.
00:12	To follow this tutorial, Learner should be familiar with topics in high school mathematics.
00:20	Here I am using, Ubuntu Linux OS version 14.04 Java version 1.7 Firefox Web Browser version 53.02.2
00:35	Using this simulation we will learn, About Cartesian coordinate system How to calculate the slope of a graphed line To save the plotted lines
00:48	How to change the slope and intercept of the line How, changing variables in a linear equation will affect the line.
00:58	An equation with two variables x and y is a Linear equation. y=mx+b Here m is slope of the line and b is intercept.
01:12	Slope signifies rate of change of y value with respect to x value. y-intercept is y value when x=0
01:26	Let us begin the demonstration.
01:29	Use the given link to download the simulation.
01:33	I have already downloaded Graphing Lines simulation to my Downloads folder.
01:39	To open the simulation, right click on graphing-lines_en.html file. Select the option, Open With Firefox Web Browser. File opens in the browser.
01:53	This is the interface of Graphing Lines simulation.
01:57	The interface has four screens, Slope Slope-Intercept Point-Slope and Line Game.
02:06	Click on Slope screen.
02:10	Screen has a Cartesian coordinate system with x and y axes.
02:16	On the right side, formula box shows formula to find slope of the line.
02:23	To calculate the slope, we can input values for y2, y1 and x2, x1.
02:31	Default values of y2, y1 are 4 and 2. And x2, x1 are 3 and 1.
02:41	A graph is plotted using the default values. Here we can see, Slope is 1.
02:49	We can change the values of y2, y1 and x2, x1 using up and down arrow buttons.
02:57	Plotted line can be saved using Save Line button.
03:02	We can hide the formula box, by clicking on red minus sign. To show the box click on green plus button.
03:11	Below the formula box, we have Slope, Hide lines and Hide grid check boxes.
03:19	If we click on, Hide lines and Hide grid check boxes, graph and grid are hidden. Automatically, Slope check box is disabled.
03:32	Let's uncheck Hide lines and Hide grid check boxes to enable Slope check box.
03:40	Notice that Graph displays value of the slope. Observe that on moving purple and yellow points, x1, y1 and x2, y2 values can be changed.
03:54	As we move the points, slope of the line changes. Observe the change in values of x and y in the formula box.
04:04	At the bottom of the screen, we have gray boxes to display coordinates of a point. These gray boxes are called as Point tools.
04:14	Drag and place Point tools on purple and yellow points to see the coordinates.
04:20	Drag the Point tools to the bottom.
04:24	Drag the purple point to coincide with origin (0, 0). Drag one of the Point tool and place it on the origin.
04:33	Drag yellow point to coincide with (5,5). Observe that slope of the line is 1.
04:42	Click on Save Line button in the formula box. Line is saved.
04:49	Drag the yellow point to (2,8). Drag the point tool and place it on yellow point. This confirms that yellow point is at(2,8).
05:02	Now Slope is 4.
05:05	Click on Save Line in the formula box. Line is saved.
05:11	Drag the yellow point to (-5,5). Drag and place Point tool on yellow point.
05:19	Now Slope is -1.
05:22	Click on Save Line in the formula box. Line is saved.
05:28	Drag the point tool back to place. Drag the yellow point to (-2,8).
05:36	Here Slope is -4.
05:39	Click on Save Line. Line is saved
05:44	We have drawn 4 lines with different slopes. Notice that steepness is related to slope.
05:53	As an assignment, Find when slope is zero and when it is undefined. Give an explanation.
06:04	Now let us explore Slope-Intercept screen at the bottom of the interface.
06:10	Click on Slope-Intercept screen. Screen opens with a line y= 2/3x+1.
06:21	Here intercept value is 1.
06:25	In this screen we can change the values of 'm' and 'b'.
06:30	Drag the purple point on y axis. Notice that purple point represents the intercept. When we move the purple point, intercept for the line changes.
06:44	The blue point is free to move across the graph. When we move the blue point, slope of the line changes.
06:53	Click on Reset button to reset the simulation. Click on Save Line. Line is saved.
07:02	Change the numerator value of m from 2 to 3 in the formula box. Notice that slope is 1 while Intercept still remains 1.
07:14	Now adjust m again to 2/3 and increase b value to 4. Notice that, the new line is parallel to the first line but intercepts y-axis at 4.
07:31	Click on Save Line. Line is saved.
07:35	Change b value to -2 Click on Save Line. Line is saved.
07:43	We have 3 parallel lines intercepting y axis at 3 different points.
07:50	Click on Reset button to reset the simulation.
07:55	Let us change b value to zero. Notice that purple point is at the origin.
08:03	Line now passes through the origin.
08:06	Click on y=x and y=-x check boxes below the slope. Notice that we have three lines passing through the origin.
08:19	Now let us now move on to Point-Slope screen.
08:23	Click on Point-Slope at the bottom of the interface.
08:28	In Point-Slope screen, a set of (x,y) values are substituted in the equation. In this method, x and y values are defined.
08:41	For a given value of (x, y), m can be calculated using the formula, y-y1 = m(x-x1)
08:53	The Generic point (x1,y1) is represented by the purple point.
08:59	Drag the Point tool to the purple point to see its coordinates.
09:04	Drag the Point tool back to its place.
09:07	Drag the purple and blue points freely across the graph to modify the equation of the line. Drag and place purple point to (5,0).
09:20	Then drag the blue point to (5,5).
09:24	Notice that line is parallel to y-axis and slope is undefined.
09:31	Click on Save line. Line is saved.
09:35	Drag the purple point along the x-axis. Notice that Slope is undefined all along the x-axis.
09:45	Now let us move on to Line Game screen.
09:49	Click on Line Game screen.
09:52	Line Game screen has 6 difficulty levels, to play. These games will test the knowledge gained using this simulation.
10:02	It has a Timer and Sound buttons at the bottom of the screen.
10:08	Click on each game and explore.
10:20	Lets summarize.
10:22	In this tutorial, we have learnt, About Graphing Lines, an interactive PhET simulation.
10:29	Using this simulation, we have learnt, About Cartesian coordinate system with x and y axes. How to calculate the slope of a graphed line. To save the plotted lines
10:43	How to change the slope and intercept of the line
10:47	How changing variables in a linear equation will affect the line.
10:53	As an assignment 1. Using Slope-Intercept screen, find when the value of slope is 1. 2. Using Point-Slope screen, find in which quadrants slope is positive.
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11:32	This project is partially funded by Pandit Madan Malaviya National Mission on Teachers and Teaching.
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11:53	This tutorial is contributed by Spoken tutorial team IIT Bombay. Thank you for joining.

Contributors and Content Editors

Madhurig, Pratik kamble, Sandhya.np14