eli5 why do we “forget” long practiced skills after a period of time of not using said skills? and how can we regain those skills

Question

i noticed that after the holidays my math plummeted and teachers told me its because of the break i took… why does this happen and how can i regain those skills acquired prior to the break

In: 356

Answer 1

Brain forgot details of tasks that you no longer practice after few times.

It is also quicker to forgot:

1 things that does not get you emotions (love, hate,fear, laugh)

2 things you used few times

3 things you learned from only 1/2 months

I took a degree in engineering and I always forgot the theorems demonstration few weeks after the exam.