This is a very useful sharing and counting activity
You need a set of objects to count and sort
You need 12 things, these could be...
- Lego bricks
- counters
- nuts
- dried beans
- shells
- buttons
We thought about going small - here's 12 corn kernels:

... but decided that counting bigger things would be easier - so we went with oranges:

It doesn't matter what you use, just collect and count 12 items.
Next, can you share the items to find half of the 12 things
Together, count them and talk about the fraction 'Half'.

Put all of the things back into one pile
Now, can you share the items into four groups to find one quarter of the 12 things?
Again, count them together, and talk about a 'Quarter'.

Put all of the things back into one pile
Now, see if you can share the items into 3 piles to find one third of the 12 things
Again, count them together and talk about a 'Third'.

Repeat this with a different number of items.
Sometimes finding one or more of the fractions won't be possible.
This is a good talking point. For example you can find a half and a quarter of 16, but you cannot find a third without cutting something into pieces.
PARENTS
If you want to take this further you could ask your child to make a lsit of the numbers they have worked with.
Which ones can be separated into halves?
Which can me made into thirds or quarters?
Which numbers are the 'best' for sharing out?
Are there any numbers which are difficult to share?