You asked

When does separation and independence occur in a child?

As a baby, your child had no idea that you and she were two separate beings. Over time though, he or she has developed various skills and has become more confident and has figured out that he or she is an individual with their own body, feelings, and thoughts. This of course, means that from now on, they want to do things her way.
From the age of 12 to 18 months, your child now thinks for themselves, and will explore on their own. They will become somewhat adventurous and try certain things that they cannot follow through. When this happens, they might become scared or frustrated at not being able to do what they want to do. Although it might seem as if their efforts were for nothing, he or she is developing an identity.
Between 25 and 30 months, your child will still be struggling for independence. They’ll wander further away from you and test just how far they can take you with certain activities, such as drawing on the walls even when you have told them not to. Also, if you try to help them in some way, they’ll more than likely say that they can do it by themselves.

More questions

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Drooling and difficulty eating can be associated with normal toddler behaviour, illness or sensory processes.
Up to the age of three, your toddler will be over separation anxiety. However, as there are so many separations in the years of growing up – pre-school, a few days away at camp, and even your child’s first year at college, bouts of separation anxiety could very well occur from time to time all through your child’s life.
As long as your toddler has plenty of space and time to play, and practice all their new physical skills, they’re probably doing just fine with her development!
Toddlers are naturally curious about everything. Instead of stifling that curiosity, you should be making every effort to promote it!
Your child’s imagination is not only a source of fun – it’s one of his or her most important early learning tools.
Young children are emotional beings. The worst thing you can do is make them stifle those emotions. Teach them how to cope with them instead, and you’ll raise a well-adjusted child.
If you want your child to grow up with a strong spiritual foundation, it’s never too young to start teaching, but remember to teach by example.
For toddlers, as with older children and adults, happiness comes from inside, not from outside.