Describe at least three conditions necessary for children to develop language during the middle and late childhood period.

I don't know what you are defining as "the middle and late
childhood period", which makes giving specific conditions difficult - they vary at
different ages.

Toddlers acquire language as they hear and
imitate and receive reinforcement for what they have done. In this sense, necessary
conditions are adequate hearing (language development for hearing-impaired individuals
is much more difficult), role models in the sense of people using language around them
for the children to hear frequently and clearly, and reactions to shape their use of
language - when a toddler says something and receives a positive reaction to the noises
s/he made, the child will remember and use that set of sounds again in a similar
situation.

As children age, development of language becomes
a process of refinement and expansion. Role models continue to play a critical part in
providing patterns for word use and meaning, pronunciation, localized slang expressions,
etc. Direct instruction may also be introduced to teach specifics of grammar or to
provide direct definitions for new vocabulary. Mental and emotional factors also
continue to be important - autistic children may have impaired language development
because they are unable to make the connections to others necessary for language
development to occur.