I have a mathematics programme in Word 2010 which will produce fractions. However, the fraction is not large enough. How can I make it larger?

You will need to provide more details of what this mathematics program is, how it produces fractions in Word 2010 (including how it determines the font & font size), what size they are and what size you want them to be.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

I am referring to the 'Mathematics' thing that you can click on which is to the right of 'Add-ins'. If you click on mathematics then on equations, the fractions thing comes up.

I think I must have downloaded Microsoft mathematics add-in

The Microsoft Mathematics Addin uses the very same Insert|Equation>Fraction tools Word already comes with. In other words, you don't need the Addin at all for inserting fractions. As for changing their font size, that requires nothing more sophisticated than selecting the fraction, then clicking the Ribbon's Home tab and choosing the font attributes you want.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

The trouble with highlighting then increasing the font size is that the whole equation gets bigger. The initial problem was that the fraction was too small in relation to the rest of the equation.

It would be helpful if you mentioned the full scope of the issue at the outset. All you originally mentioned was fractions. When using the Equation Editor, you cannot format any part of it differently from the rest. Depending on what you're doing, you might do better to simply type the fraction into the document then format the numerator & denominator however you like.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

There must be a way of changing just the fraction within the equation editor.

No, there isn't. There is no 'must be a way' about it. You either use the equation editor, with all that implies, or your don't.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]