Capability to change position or size of drawn objects while
preserving all relevant relations among them is an invaluable advantage of
dynamic geometry software over paper and traditional tools. (This is also why we
call it dynamic goemetry software.) To move an object you have to
first grab it.
4.1. Grabbing and Moving Objects
To grab an object you must position the cursor above the object (which must
become highlighted) and press and hold right mouse button. While holding the
right mouse button, move the object to the desired position.
1. Grab the point P and move it from the upper left corner to
the lower right. Does it move freely? (In other words: Are you able to place in
anywhere on the "paper"?)
In Cabri Jr., grabbing is controlled by ALPHA key. In Cabri II
(computer software) use left mouse button for grabbing.
Questions continue below.
Tutorial - Grabbing and Moving Objects
Grab and move objects (see the instructions). Observe results.
Note: No "Well
Done" message window will show in this activity.
2. Grab the point C and try to move it. What do you observe?
Does C move freely?
3. Points A and B were created on the circle.
Try to grab A and move it. What do you observe? Does A move freely?
4.
Point X was created as an intersection of two lines (the lines are hidden). Grab
it and move it. What do you observe? Does X move freely?
5.
Experiment with other points and objects. Try to grab also the circle or the
line segment AB and move them as a whole.
It is important to realize that how an object moves (and if it
moves at all) depends on how it was constructed. In your own constructions, you
should be able to explain why certain points move freely, why other are fixed to
an object such as a line or circle and why it is not possible to move some
objects at all.