4時に子供たちを学校までお迎えに行って下さいって英語でなんて言うの？

When telling someone to collect someone or something for you, you want to be clear what time they need to collect them/it, especially when the children are at school so you could say 'please pick the children up from school at 4pm'

To make a formal request for someone to pick up your children from school at a certain time (in this case at 4), you would ask "Could you please pick up my children from school at 4 o'clock?"Another variation of this question would be "can you go to the school at 4 o'clock to pick up my children?" If you would like to make an informal request, you could simply ask "can you get my kids from school at 4?"

For the first two answers: Will you please pick up my children from school at 4PM? Could you please go to school at 4PM to pick up my children? You are kindly asking the person to pick your kids up from school. You are also informing them of the time that your children will finished with school at 4 o'clock and waiting to be picked up. Please pick up my children from school at 4. This statement could mean that you have already asked the person to pick up your kids. By saying this, you are simply confirming the time that your kids will be waiting and that the person should be ready to pick them up by 4 in the afternoon.

When asking someone to go pick up my children from school, you want to ask them to go to school at 4 to pick up your children. Either of the above requests should be appropriate.

The phrases above are common in the US when asking someone to pick up their children from school at a certain time. It is important to make sure you tell the person where to pick up the children and at what time, in order to avoid any confusion or lateness. The above phrases are also less formal, if you want to be more formal with the request you can add "Can you please pick up my children from school at 4pm?".