There are websites available to provide daily lessons or daily emails. I've belonged to several over the years that I enjoyed, such as Wordsmith.Org which sends a daily email with a new word to learn. Another is Daily Grammar. My favorite of all time is THE DAILY GOSPEL. I've subscribed for years.
If you like the idea of receiving a daily email, or occasionally visiting a website for a lesson of the day, here is a long list from which to pick and choose:
Math Forum: Problems of the Week
Not daily, but once a week. From basic math to algebra to geometry.
National Geographic Photo of the Day
National Geographic hires the best photographers in the world. Awesome pictures.
Earth Science Picture of the Day
Great picture each day with an explanation.
LPOD - Lunar Photo of the Day
Great addition to astronomy lessons.
Pictures from the week in news.
Links to loads of websites that gives us the news in pictures.
WordCentral.Com - Daily Buzzword
Quotes of the Day - The Quotations Page
Can also search for specific quotes.
Quotes of the Day
Receive random quotes via email.
Astronomy Picture of the Day
We sometimes save the pictures for our computer background.
Word of the Day
Not only is a definition given, but the word is used in several examples from literature.
German Vocabulary of the Day
For beginning or advanced students.
Japanese Phrase of the Day
A year's worth of phrases are laid out for you, so you could just print them out instead of checking the Web each day, if you desired.
Today in History from Teach-nology
Gives long list of events that occurred on "this day in history." Or you
could plug in other dates, such as a child's birthdate. Might prove useful for
daily history prompts.
Today in History from the Library of Congress
More "this day in history." Has in-depth article on an event.
Space Station Science Picture of the Day
Pictures with extensive commentary
OSEI (Operation Significant Event Imagery) Picture of the Day
The Operational Significant Event Imagery team produces high-resolution,
detailed imagery of significant environmental events
If you have a favorite daily email, or website of the day, that isn't listed here, please let us know about it in the combox.