There seems to be a lack of awareness on the part of the everyday presentation creator that you can actually put text inside a square (or any other shape) object. The disadvantage to not putting the text in is that you have to deal with two objects, or group them together which makes it difficult to edit. The advantage of putting text in the box is that by making it one object you can resize it and the text will automatically resize with it.
Here is what I mean by text in a box and text not in a box:

If you are not sure how to creat text in a shape, it’s easy:
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Create a shape object.
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Select the object
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Click on the text color icon, this should place a text cursor in the shape. The text color icon looks like this:

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Start typing, once your done if you need to change placement of text in the shape, margins or wrapping – right click on the object and Format Autoshape.