Theory:

The following sentences from the lesson expresses the usage of Modal Verbs:
Shall: Indicates future action - suggestion/promise.
  1. We shall follow your advice and together protect ourselves from dangers.
Should: Note that "Being safe" is a lesson that has advice on safety rules. Hence we find maximum usage of  the modal verb "should".
  1. When you walk on the road, which side of the road should you walk?
  2. We should walk on our right-hand side, against the traffic.
  3. We should wait until the road is clear of traffic.
  4. We should first look right, left and then again right before we cross the road.
  5. We should follow road safety rules strictly.
  6. We should learn to put things back in their respective places after using them.
  7. We should not play with knives, scissors etc.
  8. These mobile phones are very useful, but we should use it with care.
  9. You should use it in the presence of adults.
  10. I think we should store all medicines out of sight and reach of children.
  11. Medicines should be kept a locked cabinet.
  12. I also think pills and syrups, should be kept in their original containers.
  13. We should keep a count to avoid misuse.
  14. Gardening products should be secured and kept locked.
  15. A first aid kit is a must in every household which should also have an emergency instruction inside it.
Will: Voluntary actions/promises for events that will take place in the future.
  1. Grandpa, we will also walk, in a line one behind the other and not in groups.
  2. How will I know, if I'm getting a sunstroke?
Could: To ask permission in a formal and polite context, to express a probability.
  1. Could you please tell us the safety measures to practise at home, grandpa?
  2. Could I have your views on using the medicines effectively?
Can: To ask permission, to express a probability.
  1. Can we take him out to play in the fields, grandpa?
  2. We should walk on our right-hand side, against the traffic, so that we can see the vehicles coming.
  3. Can we put on sunscreen before going out in the sun?
  4. We can talk more tomorrow.
May: To express a probability.
  1. Oh, it may be due to the heat.
  2. When the body cannot cool itself fast enough, we may get a heat sunstroke.
Need/need to: Instructions/necessity - generally used with infinitive "to".
  1. You need to be very careful as the Sun is scorching.
  2. But you also need more physical activities.
  3. Yes, you need to put on the Sunscreen 15 to 20 minutes before going out to avoid Sunburn.
Have to: Instruction/obligations. Can be replace by "must".
  1. They have to take him out for playing.