In this activity we use sliders to control the location of a point or a set of points.
Applet 1 shows a point and a slider. [br][br]Move the slider. The point doesn't move.[br][br]Now edit the value of the point: write A=(2+a,5) into the input bar.[br][br]The point should now move with the slider. [br][br]Notice the value of the slider and the value of the x coordinate.
Applet 2 shows a point and two sliders. The point is currently independent of the sliders. If you move either slider, the point doesn't move.[br][br]Edit the point so that the first slider controls movement left and write, and the second slider controls movement up and down. Write A=(2+a,5+b) into the input bar.[br][br]Alter the values on the sliders so that the point goes up and down alot.[br]Alter the values on the slider so that the point only goes up and down once as it travels across the screen.
Applet 3 shows a triangle and two sliders.[br][br]The triangle is defined by the points A, B and C.[br][br]Edit the points so that all three x values say ' +a' and all three y values say '+b'.
Applet 4 shows the fish and no sliders.[br][br]Imagine that the mouth closes. Where does the point LIP go? Does the 'x' or the 'y' coordinate change? By how much?[br][br]Use the slider tool to create a slider. Set the minimum and the maximum to the correct values for the LIP to open and close.[br][br]Edit the point LIP=(9,3) to include the slider. Press play to see if it works.
Applet 5 shows the fish with two sliders.[br][br]Edit each point in this way: A = (2+a,2+b) [br]or in this way: A = (2,2)+(a,b)[br]or create a point called GO (any name with upper case letters works), and edit like this: A = (2,2)+GO[br][br]Create a slider for the mouth as you did in applet 4.[br][br][br][br]
Applet 6 shows two sliders and the toolbar.[br][br]Use the tools to create and animate a shape.[br][br]You may add as many sliders as you need.[br][br]As 'reset' isn't available, you'll need to use the 'undo' or 'delete' to remove unwanted creations.
Applet 7 shows an animated fish with additional features.[br][br]Click the link [url=https://www.geogebra.org/m/chpswtpg]https://www.geogebra.org/m/chpswtpg[/url]to open the original, and use the menu to choose 'open in app'. From here you can right click on any object to see settings and to reverse engineer the applet.[br]
The letter ‘a’ on the first slider is known as a [i]variable[/i] as it is a number that changes. The[br]value ‘2+a’ is an [i]expression [/i]for the x coordinate of the point A in the first applet. [br][br]Using the words ‘variable’ and ‘expression’ explain why the sliders control the animation.