Did Christ use parables so that his teachings could be understood?

      No, Christ did not teach in parables simply that the uneducated, simple folk could understand. Jesus spoke in parables because he was a prophet speaking to a rebellious nation (Ezekiel 17:2, 24:3, Hosea 12:10), and it was these parables which were as mysterious as the mysteries they revealed (Psalm 78:2, Matthew 13:34). Parables were the sayings and riddles of the wise (Proverbs 1:6), and even Christ's own disciples had difficulty understanding his parables (Matthew 13:36, 15:15-16, Mark 4:13, 4:34, 7:17-18, John 10:6, 16:29-30). On the contrary, Christ spoke in parables for the most part so that those who heard would not understand.

        The disciples came to him and asked, "Why do you speak to the people in parables?" He replied, "The knowledge of the secrets of the kingdom of heaven has been given to you, but not to them. Whoever has will be given more, and he will have in abundance. Whoever does not have, even what he has will be taken from him. This is why I speak to them in parables: Though seeing, they do not see; though hearing, they do not hear or understand.
        In them is fulfilled the prophecy of Isaiah: 'You will be ever hearing but never understanding; you will be ever seeing but never perceiving. For this people's heart has become calloused; they hardly hear with their ears, and they have closed their eyes. Otherwise they might see with their eyes, hear with their ears, understand with their hearts and turn, and I would heal them' [Isaiah 6:9-10]."
(Matthew 13:10-15, Mark 4:10-12, Luke 8:9-10)