Theory:

Present simple tense:
Present simple tense is a verb tense form that expresses events or actions that happen continually in the present, like every day or week or month; it is also used to express events that happen usually/often and for factual information.
Example:
1. I want to sleep.
2. She does not like rice.
3. They do not wish to dance.
4. The sun rises in the east.
5. The flight arrives at 4 am tomorrow.
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Simple Present - for events happening in the present/general truths/habits/timetabled events.
 
Uses of present simple tense:
 
No.
Use
Example
1
Express habituation or Regular HabitsI play tennis every weekend.
2
General truths - facts that exist at all timesThe sun rises in the east.
3
Exclamatory sentences (beginning with here or there)
There she goes!
Here it is!
4
Expressing actions happening now. Commentary (happening
currently)
"The bear comes near the child, but the child  has no clue!"
"Ashwin bowls a beautiful ball, but it seems to have gone for a four!"
5
Future events / timetabled events
The match starts at 4 pm sharp.
The bus leaves daily at 8 am.
6
Quotes / proverbs
All is well that ends well.
A stitch in time saves nine.
7
Substitute simple future tense
If it rains, we will get wet.
As soon as he arrives, I'll call you.
 
 
Important!
It is good to note the difference between sentences that express habitual actions (events happening every day) and sentences that express current actions (events happening at the moment).
Present progressive/continuous tense:
The present progressive/continuous tense expresses an action or an event that is happeningcurrently, frequently or may continue to happen in the future.
Example:
Happening currently — She is writing her homework.
 
Happening frequently — She is always coming late for class.
 
May continue to happen in future — She is doing her masters degree.
present progressive tense_revised.svg
Present Progressive - for events in the present, or planned events to happen in the future.
 
Uses of present continuous tense:
 
No.
Uses
Examples
1
Action going on at the time of speakingShe is dancing to the new song.
2
A temporary event, not necessarily happening now.I'm learning French from my neighbour daily.
3
Event planned earlier, to happen in the future.I'm going to a movie tonight.
Examples of simple present from the lesson "Fire: Friend and Foe":
  1. We use it to cook our food.
  2. We spend more trying to find new ways of preventing fires.
  3. To burn paper or a piece of wood, we heat it before it catches fire.
  4. We generally do it with a lighted match.
  5. Every fuel has a particular temperature at which it burns.
  6. It only means that fire is very useful as long as it is kept under control.
  7. If fire gets out of control it can be very dangerous.
  8. It can be a dangerous enemy once it gets out of control.
  9. Oxygen comes from the air.
  10. They possess many skills.
  11. The oxygen in the air combines with carbon and hydrogen in a fuel.
  12. A chemical reaction takes place.