There is a lot going on here so let us try to break it down. And if my timeline is correct, this is right after Jesus' triumphal entry in Jerusalem. After making His way over to the Temple, He finds the Temple has become a den of thieves. Jesus sees what is going on in the Temple - the house of God - and He drives out all those who bought and sold, overturning the money changers' tables. Needless to say, He was greatly displeased with what was going on in God's house.
Now, in light of what we just went through, did Christ actually run all the adults out of the Temple? There is another thing that occurs here that I have never really thought much about before. Maybe being focused on the cleansing of the Temple I missed it. In verse 15, we find that the chief priests and scribes are now the ones who are indignant at what they see and what they hear. Jesus comes to the Temple and they did not want Him disrupting their business operations and they began their attacks on Him asking, Do you hear what these are saying?
And what happens next is what I have never given much thought before. I guess focusing on the cleansing of the Temple it is overshadowed. God was in the flesh right before their eyes and the adults refused to see Him. The children began to cry out, singing, Hosanna to the Son of David! Were the children the only ones who could see God? Did Jesus open their eyes to confound the mighty? Were these some of the same children that He had blessed before?
Is there anything more beautiful than a child singing to God? Is there anything more pleasing to God than His children praising Him? As we just saw, the children saw God for who He was and could not keep quiet. Perhaps this is one of those times that if the children had not cried out, the creation would have.