We have to know are example of title in investigatory project

For which subject?
Have you checked out your books for interesting topics to base your project on?

Science

Yes, but there are three main parts of science.

And are you the one who asked the question?

You should avoid making several accounts on AMHD and stick to only one as far as possible if this is the case.

I need a science investigatory project for elementary that is easy to do..

Check in your books and look for things that you'd like to learn more about. This will be interesting for you, and help you when you'll take next year's science class.

I need an investigatory project that there's something to do with a machine. Not so expensive. And not yet proven. I have no idea what project I am going to do. Will somebody give a very interesting idea that I can up with a machine which is useful to our environment.

Start your own thread next time please.

A machine? Do you have to make it?