Times
The first mishna in Masechet Brachot is dealing with this question.
When can you say Shema in the evening?
When you can distinguish between these two colors, a person can begin saying Shema in the morning.
What is, Techelet and Lavan?
Rabbi Akiva says that this klal, or principle, is the biggest organizing idea of the Torah.
What is v'ahavta l'reiecha kamocha?
He said that a person must say the Shema in the evening laying down.
Who is Beit Shammai?
Though a person can technically say the evening Shema until dawn, the chachamim said they should say Shema before this time.
What is midnight?
The second mishna in Masechet Brachot deals with this question.
When can you say Shema in the morning?
According to Rabbi Eliezer, when you can distinguish between these two colors is when you can say Shema in the morning.
What is, between Charti *green) and Techelet?
When the mishna refers to an hour as it relates to the time of day, they are referring to this.
What is a halachic hour? Give how it is calculated.
He said that a person can say Shema k'darko, however he is, whether that be sitting or standing.
In order to prevent the possibility that a person would carry a shofar on Shabbat, the chachamim made what decision about Rosh HaShanah when it falls on Shabbat.
What is, that we don't blow shofar?
This is the Hebrew term used in Brachot 1:2 for when the sun has risen above the horizon.
What is, Netz HaChamah?
This vegetable is the color of charti.
What is a leek?
When the rabbis establish a guardrail for the Torah, it is in order to accomplish this. See Brachot 1:1.
Who is Rabbi Tarfon?
So that people would not be confused when they went to the butcher, the chachamim forbid the consumption of cheese with this food.
What is chicken?
This time is when the light of the sun begins to light up the sky but is not yet visible.
What is dawn, or Amud HaShachar?
Most people do not include this color in the strings of their tallis because they are unsure as to how to accurately produce the dye in today's age.
What is techelet?
Apart from the fact that we don't hold like Beit Shammai, because of this principle, what Rabbi Tarfon did while laying down when saying Shema was wrong. (Hint: look at the verb in Brachot 1:3).
What is sakana (danger)?
He famously held that one can say Shema until dawn, which we know from an incident when his sons came home late from a wedding, and he instructed them to say Shema.
Who is Rabban Gamliel?
One could argue that this suggestion of Shammai's is a siag latorah that helps a person stay on track with the mitzvah of learning Torah.
What is establishing regular times to learn?
This is how the time of Tzeit HaKochavim is described in the Brachot 1:1.
What is, from the time when the Kohanim ate their Trumah?
The Gemara identifies this fish as the source of the color techelet. (Hint: footnote of Brachot 1:2).
What is the Chilazon?
Rabbi Yehoshua's ruling that a person can say Shema until three halachic hours after sunrise (when princes rise) implies what.
What is, that all Jews are bnei melech, that all Jews are the children of a King?
He holds that a person can say Shema until three halachic hours after sunrise, which is the time that bnei malachim rise.
Who is Rabbi Yehoshua?
Candle lighting for Shabbat, which signifies a person accepting Shabbat, is this (holy Jewish-) number of minutes before Shabbat begins in order to prevent a person from doing work on Shabbat.
What is eighteen minutes?