לפני שיצאתי מהבית מדדתי חום עם מדחום חדש.

לפני ש- means before followed by a full clause.

So:

• לפני = before
• שיצאתי מהבית = I left the house / I went out of the house

Together, לפני שיצאתי מהבית means before I left home.

Hebrew often uses לפני ש- where English uses before + subject + verb.

The ש is a shortened form of אשר in modern Hebrew, and here it functions like a connector meaning something like that / when depending on context.

After לפני, Hebrew usually says לפני ש... + clause.

So:

• לפני שיצאתי = before I went out / before I left

It is attached directly to the next word, which is very common in Hebrew spelling.

יצאתי is the 1st person singular past form of the verb לצאת, meaning to go out / to leave.

The ending -תי often marks I in the past tense.

So:

• יצאתי = I went out / I left

This form does not show gender. A male speaker and a female speaker would both say יצאתי.

מדדתי is also 1st person singular past, from the verb למדוד, meaning to measure.

So:

• מדדתי = I measured

Again, the ending -תי shows I in the past tense, and it is the same for both male and female speakers.

Because Hebrew often leaves out subject pronouns when the verb already makes the subject clear.

Both:

• יצאתי = I left
• מדדתי = I measured

already contain the idea of I.

Adding אני is possible, but usually unnecessary unless you want emphasis or contrast.

Because מ־ meaning from is a prefix in Hebrew, and it attaches directly to the following word.

So:

• מ־ = from
• הבית = the house / the home

Together:

• מהבית = from the house / from home

Also, when מ־ comes before ה־, the form often contracts in this way.

In this sentence, מהבית most naturally means from home or out of the house.

Even though הבית literally means the house, Hebrew often uses the house where English would simply say home.

So the phrase can be understood naturally as:

• before I left home

Because חום here is being used in the common expression למדוד חום, which means to take one’s temperature.

Also, את is normally used before a definite direct object. Here, חום is not definite in the sense of the temperature. It is more like a general noun inside a set expression.

So:

• מדדתי חום = I took my temperature / I measured my temperature

Using את החום would sound different and much less natural in this context.

Literally, חום can mean heat. But in everyday Hebrew, in the phrase למדוד חום, it usually refers to body temperature, and often by implication checking for a fever.

So in this sentence, חום is best understood as:

• temperature
• or more specifically body temperature

This is a very common everyday usage.

עם usually means with, and here it introduces the instrument used to do the measuring:

• עם מדחום חדש = with a new thermometer

So the sentence is saying that the speaker measured their temperature using a new thermometer.

This is a natural way to express the instrument in Hebrew.

Because it is indefinite:

• מדחום חדש = a new thermometer

If it were definite, it would be:

• המדחום החדש = the new thermometer

So the sentence specifically means the speaker used a new thermometer, not the new thermometer.

In Hebrew, adjectives usually come after the noun they describe.

So:

• מדחום חדש = a new thermometer

This is the normal Hebrew word order for noun + adjective.

If the noun is definite, the adjective also becomes definite:

• המדחום החדש = the new thermometer

The sentence begins with a time clause, then gives the main action:

• לפני שיצאתי מהבית = before I left home
• מדדתי חום עם מדחום חדש = I took my temperature with a new thermometer

So the structure is:

• time clause
  • main clause

This is very natural in both Hebrew and English. The Hebrew sentence could also be reordered, but this version sounds smooth and normal.

Yes: the most useful chunk to remember is למדוד חום.

It is a common expression meaning:

• to take one’s temperature
• to check for a fever

So even if you know that חום literally means heat, in this expression you should think of body temperature. This is one of those everyday combinations that is worth learning as a unit.