Englishfor English speakers
least
Determiner
—
the smallest amount of; little of
She does the most cleaning, but the least cooking.
No German, least of all the East Germans, wanted Soviet troops to stay.
least
Adverb
—
Having the smallest amount of a characteristic in a group.
People are least likely to live in the far north.
The phone always rings just when you least expect it.
least
Adjective
—
The least is the smallest amount.
There are at least four problems with the idea.
The power is least in this case.
The least difference is still important.
Nobody works hard, but she does the least.
He was not the least bit interested my ideas.
This accident is the least of our problems.
effective
Adjective
—
An effective strategy, treatment, method, etc is one that works well as planned.
Teachers are using instructional strategies that are most effective in helping students learn.
—
If you have effective command, consent, control, etc., you have it in practice but not officially.
The students had effective control over what the teacher would include on the test.
—
If a law, agreement, change, etc. becomes effective, it officially begins.
The new rules about ball size are effective next season.
effective
Preposition
—
You use effective to say when something starts officially.
Effective next week, all employees will wear the new uniform.