What I tell my students about conclusions is that you should have three main parts.

First, restate your thesis. The thesis is your main argument of your essay. It sounds like the thesis is something about how parents should not be too materialistic and greedy. This is certainly a major theme in the short story "The Rocking-Horse Winner". You probably want to change he wording of your thesis and perhas introduce it by saying something like, "As I stated..." or "It is certainly clear that..."

Second, revisit the supporting points you used in your essay to prove the thesis is true. These would most likely be the topic sentences of your body paragraphs. In most essays, there are three body paragraphs and three points. You probably want to change them around a bit too.

Some supports you may have used for this particular thesis on this story are:

1--The parents' worries about money infect their son's life and contribute to his gambling problems.

2--The parents' over-concern for climbing the social ladder lead them to pressure their children, leading to their son's death.

3--The parents greed leads the family to try dangerous ways to show their love.

Of course, you may have different/better body paragrah topics. Please check in the body paragraphs to make sure you use textual support (quotes,etc.) to illustrate whatever points you are using.

In the conclusion, you should probably just write one sentence about each point, putting it in slightly new words from the way you stated it in the body paragraphs and introduction.

The last part of a good conclusion wraps everything up and inspires the reader. You might try two or three sentences that follow a pattern like this. I am giving you examples of ways I might finish these sentence stems in an essay on this thesis.

1--Make your point forcefully.

"As you can see..." parents can have a great impact on their children's lives, and in this case, the parents' greed and materialistic thinking led to Paul's destruction.

2--Make a connection to the present day/real world.

"In life..." we should all focus on the important things that money canot buy, like family ties, love, support, and authenticity.

3--Inspire your reader to change things in life. "So please..." appreciate all that life has to offer that is not bougt and sold, and know that your focus is in the right place for your kids and families.

Hope this helps!