There are a number of words that have more than one reading in Japanese. Sometimes, as shown by this webpage, it’s a matter of the reading changing over time. For example, I read somewhere that 「世論」 is supposed to be read as 「よろん」 but so many people misread it as 「せろん」 that it eventually emerged as an alternative reading. For words like this, choosing a reading is merely a matter of preference and depends on the popularity of the reading since the meaning is the same. However, some words have different readings and different meanings to go with them. We’ll look at two that I can think of right now (「頭」 and 「家」) and how you would identify the correct reading.
-I want to go home because my head hurts.
-In his house, there are 3 children, 14 being the oldest.
In the first sentence, 「頭」 is talking about the speaker’s head (the thing on your neck) and so we should read it as 「あたま」. However, in the second sentence, we are talking about the 14 year-old being at the head of the rest of the children. When we are using 「頭」 to mean “head” as in “chief”, or “the first”, we read it as 「かしら」. Amazingly, the English word for “head” also contains both meanings (though we don’t change the reading).
Finally, 「家」 can have two readings depending on whether the speaker is talking about his or her home or just a generic house owned by anybody. Your own home is read as 「うち」 which probably has something to do with 「内」（うち） meaning inside. The reading for a generic house is 「いえ」 (not to be confused with 「いいえ」).
So in order to figure out when to use which reading, 1) learn the difference in meaning, and then 2) look at the context of the sentence. So can you identify the correct readings for 「家」 in the examples sentences?