Reading over your memory draft, it may make more sense to start with a narrower focus. Discussing all of child development is very broad, however, your focus is on social judgment and aggressive behavior. Think about why this narrow topic is important and what you can do to make it more clear in your introduction. 
The Introduction is vey broad  you should funnel-shaped introduction. It should  leads you step by step down to the very narrow point of your essay (the thesis). The first sentence of the introduction should get the reader’s attention.  you can mention why the study is important ?

I did yellow highlight for the sentences that need to be fixed. (These are the first sentences of each paragraph) . They are very broad try to narrow them  a topic sentence  or first sentence should summarizes the main idea of a paragraph. Also known as a focus sentence.
Re do the conclusion because you are adding new idea this should  provide the reader with a sense of closure on the topic.