You can pour milk into plastic bags and freeze it but you could also freeze the milk in ice cube trays first and then put the ice cubes of milk into the plastic bag.
Or just freeze the milk in plastic containers such as soda bottles, water bottles etc and then thaw it out to use it.
Yes milk can be frozen in ice cube trays.
I like to use ice cube trays to freeze milk in and ti works perfectly then you can also put the frozen ice cubes of milk into plastic bags and then thaw it out and drink or use the milk later.
Or add the frozen milk ice cubes to recipes that require cooking or baking and the heat will melt the milk into the recipe.
Frozen milk will last for a year but it's best to consume the frozen milk within 6 months of freezing it because the taste really changes the more you leave it in the freezer.
Frozen milk can also turn yellow which is normal and nothing harmful about it although it may not taste as good.
it's due to a chemical reaction of the milk and water and both the milk fat and water separating when it's frozen and then thawed out.
Once thawed out the frozen mil should be consumed within a few days before it goes bad.