Introduction

The other night, after you finished your homework, you go out for awalk. Out of nowhere, a strange looking alien, hovering in a spaceship appears.

He says, "Вы 7th грейдер?" "WHAT?" you shout! The alien punches a few buttons, and he says "Are you a 7th Grader?" You stutter "Y-y-y-y-yes."

"Have I got some questions for you! I know you have learned all about matter. You must have a fantastic science teacher! I want you to explain what you know about matter. That way, I can compare it to what I have learned and see if we know the same thing!" You do nothing.

"Don't stare at me," he shouts. "Get to work and answer my questions." Being an obedient student, you go to the Task Section and begin to work!

The First Task

• Explain what you know about atoms and molecules.
• Identify problems with atom models.
• Outline a history about how we learned about matter.
• Identify properties of a solid, liquid, and a gas.
• Draw a picture showing particle movement in a solid, liquid, & gas.
• Compare motions of particles at different temperatures.
• Explain diffusion.
• Define and show how density is calculated.

As you do your research, complete your worksheet. (Note: If you already have a worksheet, DO NOT click on the link!)

To answer the questions on your worksheet, you will need to visit sites on the Internet. Every question can be answered by going to one of the websites listed. This doesn't mean that you will find everything at one site. You will have to explore, read, and learn about the principles of matter.

Use these websites for your research.

The Second Task

Another property of matter is density. (Click here for a definition of density).

On your worksheet, complete the appropriate density problems on the Word Problem Exercise Page.

On occasions, you are required to find the density of an irregular object. To do this, you will use water displacement. Review this webpage to refresh your memory about water displacement.

Your next challenge is to complete the Float or Sink worksheet. Go to this website and complete the interactive activity.

Your final density challenge is to complete this interactive density lab. (Ooops! Forgot how to use a triple-beam balance? You can review how to use a triple-beam balance here.) Write your answers on your worksheet.

Conclusion

As you leave school after you've finished your worksheet, you see you alien friend gliding over on his hoverboard. He glides up and you hand him your completed worksheet. He looks it over and smiles. He tells you, "This is just what I learned on my planet. The principles of matter are the same on my planet and Earth. Thanks for all you work. Now, I don't have to do my homework. I'll just copy yours!" and flies off.

You become really upset. This is the last thing you wanted to do - do homework for an alien. You don't even have your worksheet to turn in. What are you going to do? You decide that your teacher won't believe you if you said "An alien stole my homework." So, you decide to use that time honored, student excuse. He just might believe that story!