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The Only Way I Will Ever Teach Density

Raise your hand if you’ve ever sat on your suitcase to zip it up. No one is here to judge you. I know I’m not the only one. 

When I get to the airport, I anxiously place my suitcase on the scale and pray I’m under the 50 pound limit. So far, I’m at a 100% success rate – thankfully. 

Now that you know my travel habits…

I give you this word picture because it directly relates to how I talk about density with my middle school students. 

The concept of density is kind of tough to grasp. It’s very concrete, but it’s also very abstract. Do your students grasp it? 

Density is defined as the degree of compactness of a substance. Mmmmmkaayy….? Your sixth or seventh grade student can’t really wrap their head around that. 

You might try and explain it by saying it’s the amount of stuff in a certain space. Give them two objects that are the same size and are drastically different in mass. Closer. That is a little more concrete. 

What about a suitcase?

You’re going on a trip with a friend … let’s say to Bora Bora. The airline will only let you bring a standard carry on suitcase. Both of your suitcases are the same size.  In fact, they’re identical.

You are an overpacker. The kind of person I talked about earlier. Where you have to sit on the suitcase to zip it. 

You pack 14 shirts, seven shorts, three jackets, two different curling irons, 7  pairs of shoes – including rain boots… just in case, and three bathing suits, and a few other things you need for your trip. 

Your friend is a light packer. For the same trip, they pack six shirts, two pairs of shorts, a hairbrush, a jacket, a bathing suit, and two pairs of shoes. 

Are you still with me? Here’s what we’ve been building to. 

Whose suitcase is more dense?

Each one of those items is now a piece of matter. Remember… both of your suitcases are the same size. Which one is more dense? 

Yours. The one you had to sit on to zip! It’s more dense because it has more matter in it!

The suitcase with more matter has more mass and is more dense. It’s going to be heavier too. There is less air in between the matter. It makes your stuff more compact and less likely to move around inside of your suitcase. 

In contrast to your friend’s suitcase, there is less matter. The suitcase will be lighter, and there is more air or space between the matter. It’s less dense.

Students identify with this story! They either are one or know both types of packers. By capitalizing on an idea they are familiar with, you can easily illustrate the abstract concept of density in your middle school science class! 

For a great inquiry experiment about density, check out this video and supporting materials on the Teaching Channel

Chemistry, Middle School

The Perfect Chemical Change Lab for Middle School Students

Have you ever accidentally dropped bleach on a shirt? It’s ruined. Completely and totally. What I never realized was a chemical change is created between the dye in the shirt and the bleach.

I was overwhelmed the first time I taught middle school chemistry.

The supplies I thought I needed seemed so complicated. In reality, chemical changes occur all around us. Teaching this became a matter of utilizing simple examples students encounter every day.

Lab Objectives

Teaching students how to identify a chemical change does not have to be hard. In fact, you can use this Chemical Change Lab to demonstrate a simple chemical change with a few items you can find in your science classroom (or kitchen)! 

I love using labs that have multiple objectives. More objectives means more diverse student learning. This Chemical Change Lab meets the following objectives: 

  • Lab safety procedures
  • Measuring liquids using the metric system
  • Identifying a chemical change
  • Using evidence from the lab to write a clear conclusion

(TIP: If you use notebooks, you can copy the answer pages at 80% and students can glue them into their notebooks.)

Completing the Lab

The lab itself is very easy. Students add vinegar, bleach, and hydrogen peroxide to three different test tubes filled with colored water and determine which one shows a chemical change. 

Give students a chance to write a hypothesis and explain their reasoning before the lab starts. I ask them to write this alone to encourage independent thinking. However, collaborating with peers to write a hypothesis is a great option too.

Be sure to tell them they’re not supposed to be right. That’s why we’re testing it!

This lab includes so many simple steps. All the students will have a chance to measure, pour, or swirl… they are so engaged! The test tube with bleach poured into it will show a chemical change. The water turns a lighter color than the water in the other test tubes. 

(If you need a simple way to group students for labs, check out my Grouping Cards on TPT. Read about how I use them here!)

After the lab, students write a conclusion explaining whether their hypothesis was correct or incorrect using evidence from the lab.

While this task may be simple, students get the opportunity to think critically and write about it. It’s also an easy check for me to see who needs some additional support!

Why It’s Perfect

The simplicity of this lab is perfect. While middle school chemistry can be intimidating, this lab is not. The explanation, execution, and clean up time easily fits into the 45 minute class period.The materials are easy to find, the steps are simple, and students are amazed to see how the bleach makes the color of the water lighter!

Get your copy of the Chemical Change Lab here!

For more middle school science content, check out my Teachers Pay Teachers store!

Chemistry, Hands On, Labs, Middle School