Hi and welcome to VBAX

This is possible. And in less than 3 days

If you also add the textbox, then select it, go to Slideshow>Custom Animation and add an "Entrance" effect.
Then right-click the item on the animation list and select "Timing".
Here, you can choose "Start the effect on click of:" and select your button from the list.

If you have PowerPoint 97 the steps may be a little different.

Hope that helps