Which parts of Shema require kavana?

A person must have a proper understanding of the words and ideas in the first pasuk of Kriyas Shema and Boruch Shem. This halacha is separate from the general concept that mitzvos require intent (to be yotzei the mitzvah). If one did not have kavana, he must repeat the entire parsha. If he did not have kavana during Boruch Shem and continued with V’ahavta, he does not have to go back. The poskim disagree about whether it is sufficient to have kavana immediately after one finished the pasuk.

סעיף ד וס"ק יב ו־יד; ביאורים ומוספים דרשו, 14 ו־17

Is “shushing” permitted during Kriyas Shema?

It is forbidden to talk during all three parshios of Shema. During the first parsha it is also forbidden to signal or motion, even for the sake of a mitzvah. Some poskim say that signaling is only forbidden while one is saying the words, but pausing is permitted in order to signal. Others do not make this distinction. Some poskim are stringent and do not allow motioning even when saying the second parsha. All agree that signaling for a mitzvah is permitted. Some poskim are lenient in the case of signaling someone to stop being disruptive.

סעיף ו, ס"ק יז-יח וביה"ל ד"ה לא; ביאורים ומוספים דרשו 23, 26, 27

Which parts of Shema are Torah obligations?

There are three opinions regarding which sections of Kriyas Shema are mid’orasia and which are only mid’rabonon: 1) only the first pasuk is min haTorah, 2) the entire first parsha is min haTorah, and 3) the second parsha is also min haTorah. All agree that while the third parsha (which discusses yetzias Mitzrayim) is min haTorah in concept, its placement in Kriyas Shema is only midrabonon. The pasuk of Boruch Shem is also only mid’rabonon.

ס"ק טז; ביאורים ומוספים דרשו, 2

• A person may recite Kriyas Shema while in any position—whether sitting, standing, walking, reclining, or riding on an animal. When reclining, though, one may not say Shema while lying directly on his back or stomach. A slight tilt to the side is also not acceptable.

• One may stand (during Shema) to respond to Kedusha. The poskim are also lenient in allowing restless people to stand up and sit down during Shema.

• Although one may read Shema while walking, he must stop when saying the first two pesukim. A person can only achieve proper kavana (which is necessary when saying these pesukim) when he is stationary.

• Can the parshios of Shema be recited out of order?

• What must be repeated if a word was omitted?

• Which pasuk is found in both parshios?