Lesson: Sink or Float

We are now beginning our unit on density and buoyancy and I like to use this learning activity to introduce density. Making students aware of their misconceptions is one of the most powerful methods in teaching science. When you demonstrate the actual reality of the concept it can break their misconception and students are forced to change their thinking. I give the students the following challenge statement (word document):

“Ojbects that are high in mass sink in water.”

Students have to write a paragraph stating if they agree, disagree, or are somewhat in between with the statement. They have to explain in detail their reasoning. It is not important that they are actually right or not, they just need to be able to clarify their thinking. I then do the following (see video below).

Afterward the students need to explain in a paragraph if their thinking has changed and if so, they need to explain how. The items that were used in the demo can be found at Educational Innovations. Here is a list of the items, with their masses and densities (excel spreadsheet).

Lesson: Egg Saver

The egg drop is a staple of science classes. I love the egg drop. It is one of the few learning activities where all students can construct an apparatus that doesn’t require a parent to take over the student’s work, doesn’t require expensive or hard to get materials, and hey you might get to see eggs break! I like to do my version of the egg drop at the end of the year when middle school students are getting a major case of spring fever. I call my version of the egg drop, the Egg Saver project. I introduce the project by showing the students the video tittled Understanding Car Crashes: Its Basic Physics. The video, made by the Insurance Institute for Highway Safety, is hosted by a high school physics teacher and demonstrates how inertia, momentum, and impulse are essential in designing safe cars. We next go over the project parameters. The parameters are designed so that students must construct a container in which an egg can be quickly inserted and then extracted after a drop. Also no liquids or packing material are allowed. These rules are implemented so that students design a container that that has to conform to real life requirement like a car. Passengers need to be able to get into and out of a car quickly and passengers in a car are surrounded by liquids. I ban packaging materials so that students are a little more challenged. The size requirement is because I want it to be more car size than tractor trailer size, and it also forces students to be a little more creative. I then give the students the handout (word document) to the project. The project has 5 parts:

Part 1: Preliminary Design & Materials List
Students brainstorm and write a brief description of what their egg saver container would look like and how it would work. They also must write a list of materials that they might use. The purpose of this part is to get them started, which is the hardest part. They do this in class so that I know they have something written down.

Part 2: Final Design Specifications
Students have to draw a detailed diagram of their final container that shows the parts, dimensions, and the functions of the parts.

Part 3: Data Collection & Analysis
Students collect data on the mass of the egg and container, height dropped, time from release to impact, velocity, and momentum.

Part 4: Graph of Data
Students construct a line graph that shows momentum versus height.

Part 5: Final Analysis & Conclusion
Students write a paragraph that discusses the results of the experiment.

For an incentive to design a container that works, if a student’s container is successful at the highest height, 14 feet, the student is exempt from doing part 4 and 5.

We do the drops in the classroom with a 10 foot ladder. My classroom has a high ceiling which can accommodate the tall ladder. Watch a video of design that works.

Lesson: DNA Extraction

I’m using a wonderful tool called Voicethread to demonstrate how to extract DNA from raw wheat germ. Click play on how to do the demo and to see how Voicethread can be used. Download the handout for more details.

Video Demo: Lava Lamp

A while back I posted an item from Steve Spangler’s Science site that demonstrated how to make lava lamps. I decided to go ahead and try it and I filmed it. The materials that are required for the demo are shown below. As the video shows the peanut butter jar is filled with 3/4 vegetable oil and 1/4 colored water. Place an 1/8 of an Alka-Seltzer tablet into the jar. The Alka-Seltzer reacts with the water to form carbon dioxide gas bubbles. The gas is less dense than the water or oil. The carbon dioxide gas bubble attach themselves to the colored water, causing them to rise to the surface. When the gas breaks through to the surface the higher density colored water droplets sink back down into the jar. The second part of the video shows the same demonstration, this time in a large test tube.

12 Reasons Why Teachers Enjoy Summer Vacation

We're now into three weeks of summer vacation and I've fully surrended to it.  I figured I'd better make a list before summer is over, so here it is.

1. Naps.  A summer day is incomplete without a nap.
2. Low stress.  What is there to worry about?  Not much.
3. Lack of constant recurring "Mr. Fix" questions, requests, or complaints from middle schoolers. When I see a middle schooler out and about, it's very comforting to know that I don't have to worry about their behavior.
4. Weekdays are just like weekend days.  What day is it today?  I don't know.  Sundays are like Tuesdays.  Saturdays are like Mondays. There is nothing more satisfying than going to a late movie Sunday night and not worrying about going to work the next day. You almost feel sorry for those saps that have to go into work Mondays.  Almost.
5. No parent emails.  I don't have to cringe when I check my work email (why would I check my work email?) and see those helicopter parents' names in the inbox.
6. Running errands during the day.  It's not enjoyable to do errands, but it is more pleasant to go into a store at 10am on a weekday when stores are less crowded.
7. Exercise.  I can do any kind of exercise, any time during the day, then of course take the required nap after.
8. Trips.  I can take that hiking trip, biking trip, trip to the lake, etc.
9. Chores.  Not fun, but I have time to do them, and time to procrastinate.
10. Read.  I don't have to feel guilty reading instead of correcting papers, lesson planning, etc.
11. Summer still has a special place in my life.  Most adults don't get to enjoy summers anymore.  It was a special time only during childhood.  I glad I don't have to give that up.
12. Recharge my brain.  When summer ends (shudder), I will be more than ready to take on the new school year with fresh new ideas.

My only complaint about summer break?  It's way too short.