Dive Papa Dive!


TOPIC:    Engineering a diver in a bottle                         GRADES:  K, 1, 2

STANDARDS:  Science- Engineering- K-2.E.2  and SEPS.6, Physical Science 1.PS.1, History- 1.1.1

Materials needed:

BookPapa’s Mechanical Fish, by Candace Fleming

Half of a drinking straw for each student

4 paper clips per student

1 medium-sized rubber band per student

1 clear plastic bottle (with cap) per student (These might take a while to collect, so give a week or two for students to bring them in.)

1 large container, to fill with water so that students can test to see if their divers float before putting them in the bottles.

Water- to fill each bottle, and the testing pool


Time needed: 30-45 minutes (45 minutes is much better, because then students can test the divers, and make adjustments if they don’t work right away.)

*Note:  I made a diver in a bottle of my own to bring with me and demonstrate after we read the book.  Students were amazed and then excited to build their own.

Engage: Tell students that today’s story will center around a man who invents a “mechanical fish.”  Show students the book cover and ask if they know what the mechanical fish might be.  (I had a few 2nd graders who guessed it was a submarine by looking at the cover.)  Explain what a submarine is, and that the word part, “sub” means “below,” and the word part “marine” means “water.”

Read the book to students, pausing to make predictions, share connections, and ideas. (There is a great pattern that evolves in Fleming’s writing that students will notice: Papa thinks of the idea, attempts to make it, fails, gathers information from his family, and makes changes to perfect the invention.)

They love predicting at the end that Papa will go back to his workshop and build a “mechanical bird,” because he is asked if he ever wonders what it’s like to be a bird.

Papa’s enthusiasm is contagious, and at the back of the book, we learn that the book and Papa were based on a real inventor, named Lodner Phillips, who really did take his family on an excursion under the water in Lake Michigan.

I did not read the entire description of Lodner Phillips, and instead paraphrased it.  It is long, and I was working with 1st and 2nd graders, and I usually only had 30 minutes to complete the lesson.

I was, however, sure to include that one of Lodner’s inventions was “diving armor,” that helped to bring up treasures from shipwrecks.

Explore: Ask students if they are ready to build a diver that will dive under water at their command.  Hand out supplies (except water bottles- save those for later), and take students through the steps to build their own diver in a bottle.

Step 1:

Take half of a drinking straw, and bend it in half, wrapping the rubber band around the bottom where the two halves come together.  (The straw doesn’t need to have the “bendy” part.)  I tell students that either half will work, as long as they don’t crush the straw flat.

Papas Mechanical Fish diver step 1

Step 2:

Take each paper clip (4 total), and hook it over the rubber bands, all around the diver.  When finished, the paper clips should be evenly placed around the diver, so that it could stand up like a rocket ship on the desk.  The kids loved testing this!  This test helps insure that the diver is evenly weighted, so that it floats straight up and down in the bottle.

Step 3:

Let the students test divers in the big container with water to see if they float.  (This is easier than having students put them in the bottle, only to find that the diver sinks to the bottom and won’t come up.)

If the diver sinks, adjustments will need to be made.  Ideas to try may be:  1)  Make sure the straw appears to have air in it.  If it is crushed too flat, the diver may sink. 2)  Add or remove paper clips- it may be that there is too little or not enough weight. 3) There should be two holes at the bottom of the straw, but there should not be a hole anywhere on the straw.  Check to make sure.papas-mechanical-fish-diver-in-pool-e1489260285997.jpg

Step 4:

After students are sure that the divers float, hand out bottles with water inside and caps on top.  Instruct them to take off the cap, drop the diver in, and twist the cap back on tightly.  Again, at this step, if the diver sinks, it is not going to work.  The bottle will need to be dumped, and adjustments made to the diver.

Papas Mechanical Fish diver 2

Last Step:

Dive Papa Dive!  Instruct students to use both hands and squeeze the bottle.  The diver should drop to the bottom of the bottle.  When the student releases grip on the bottle, the diver will float back to the top!  See if anyone can get the diver to “float” in the middle of the bottle.


So, why does this work?  First, there is a small air bubble inside the diver that is created when we build it with the rubber bands and paper clips.  When we squeeze the bottle, we put pressure on the air inside the diver, momentarily changing its density (or how tightly the air molecules are packed together).  When the air molecules are squeezed together, the air temporarily becomes heavier than the water, and the diver sinks.  When we let go, the pressure is released, so the air molecules spread out, and the air becomes lighter than the water.