Theory:

In English, a word consists of three parts - root words, prefixes and suffixes.
A root word is a word that can form the basis of new words by adding affixes (prefixes or suffixes).
 
Prefixes and suffixes are not words by themselves, but they help in forming new words. A word that is added before a root word to form a new word is called prefix. A word that is added at the end of a root word to form a new word is called a suffix.
root words.jpg
  
Prefixes are words added before a root word to derive a newer meaning. Let us explore the usage of prefixes in detail:
1. Prefixes that derive antonyms/opposites: The prefixes "anti", "de", "dis", "un", "in", "im", "ir" usually denote the opposite meaning of the root words.
Example:
social - antisocial
lock - unlock
agree - disagree
motivate - demotivate
active - inactive
reversible - irreversible
possible - impossible
2. Prefixes that mean "cause to": The prefix  "en" usually denotes the causing effect.
Example:
able - enable (cause to able)
joy - enjoy
danger - endanger
3. Prefixes that mean "before to": The prefix "fore" usually denotes anything done before/earlier (denotes the verb).
Example:
cast - forecast
go - forego
father - forefather
4. Prefixes that mean "amongst": The prefix "inter" usually denotes amongst others.
Example:
national - international
state - interstate
5. Prefixes that mean "middle": The prefix "mid" usually denotes being in the middle part or position.
Example:
day - midday
night - midnight
week - midweek
ocean - mid-ocean
6. Prefixes that mean "doing again": The prefix "re" usually denotes repeating of an action.
Example:
start - restart
do - redo
write - rewrite
7. Prefixes that mean "too much": The prefix "over" usually denotes too much or a lot of
Example:
do - overdo
load - overload
8. Prefixes that mean "before": The prefix "pre" usually denotes previous to, before
Example:
historic - prehistoric
view - preview
plan - preplan
9. Prefixes that mean "under" and "above": The prefix "sub" usually denotes under, and "super" denotes above
Example:
text - subtext
marine - submarine
natural - supernatural
market - supermarket
10. Prefixes that mean "little or low": The prefix "under" usually denotes lesser
Example:
estimate - underestimate
age - underage
Here is a list of commonly used prefixes:
 
Prefix
Meaning
Examples
antiagainstantisocial
de, disopposite, notdehydrate, disengage
en, emcause toenable
forebeforeforego
in, iminto, notimmoral, inedible
in, im, irnot, oppositeimpossible
interamonginternational
midmiddlemidway
miswrongmisunderstanding
nonnotnonsense
overtoo muchoverdose
prebeforeprehistoric
redoing againrestart
semihalfsemi-finals
subundersubmerged, subtext
superabovesupernatural
transacrosstransnational, transport
unnot, oppositeunlock
underlittleunderestimate
 
The prefixed words in the lesson are:
  1. Antifreeze.
  2. Misuse.
  3. Indoors.