I cant grasp half life - the study guide question is how is half life dating used by scientists -

I have 2 lines to write an answer

Half life is the time it takes for 1/2 the material to decay into something different. If you start with 100 marbles, (and they had a half life of 2 days), you would have 50 marbles at the end of 2 days, 1/2 of that or 25 at the end of 4 days, 12.5 at the end of 6 days, 6.25 at the end of 8 days, etc. You can't put all of that into two lines but that's the idea of half life. How do scientists use it.

Scientists know the half life of certain radioctive elements. By measuring the activity of the element today, scientists can determine how old the material is.

Half-life dating is a common technique used by scientists to determine the age of materials containing radioactive elements. To understand how it works, we first need to understand what half-life is.

The half-life of a radioactive substance is defined as the time it takes for half of the parent radioactive atoms to decay into stable daughter atoms. This is a constant value that is unique to each radioactive element.

To use half-life dating, scientists measure the ratio of parent to daughter atoms in a sample and calculate how many half-lives have passed since the material formed. By knowing the half-life of the particular radioactive element, scientists can then determine the age of the sample.

For example, if the half-life of a radioactive element is 1,000 years and a sample has only one-quarter of its parent atoms remaining, it means that two half-lives (2,000 years) have passed since the material formed.

In summary, scientists use half-life dating to determine the age of materials by measuring the decay of radioactive elements and calculating how many half-lives have elapsed.