STEM Club: Arthropods

We wrapped up our study of invertebrates this week with a focus on the Arthropod Phyla.  I opened class with a short lecture portion, again encouraging the kids to take notes on the chart I had created the previous week or directly into their notebook.


  • hard exoskeleton which they molt several times as they grow
  • bilateral symmetry
  • jointed appendages (legs and antennae)
  • largest animal phyla – more arthropods than any other animal


  • insects – 3 pairs of legs
  • arachnids (spiders & mites) – 4 pairs of legs
  • crustaceans (crabs & lobsters) – 5 pairs of legs
  • millipedes & centipedes.

I had stations set up around the room introducing the kids to the diversity of insects (each station focused on a characteristic of a specific insect order).  Each station had a card (with printed instructions), a photographs, and at least one actual specimen to observe with a hand-lens.  I have created a slide presentation that you can use to simulate these stations with your students.  Though helpful and certainly of interest to the kids, the actual specimens are not required.  You can download the presentation here:  Insect Classification.

hands-on science activity

Upon concluding the first activity, I then introduced the inquiry portion of the lesson.  I had purchased in advance several live arthropods – 3 Madagascar Hissing Cockroaches (Class Insects, Order Blattodea), Bumblebee Millipedes, and a dozen or so pill bugs (Class Malacostraca [Crustacea], Order Isopoda).  The kids were divided into small groups and instructed to devise a simple experiment to test an experimental question.  For example,

What food(s) do the cockroaches prefer? 

What temperature do the pill bugs prefer?

Do pill bugs prefer light or dark?

isopod inquiry activity

Each group was allowed to utilize any number of the things I had on hand to set up their experiment – cardboard boxes, paper towels, ziplock baggies, aluminum foil, a variety of food (oatmeal, grapes, carrots, crackers, etc.)  I was delighted to see how well the kids worked together in the limited time we had to complete the activity.  Each group was able to quickly decide upon a question and devise a way to test their hypothesis.  However, we did not have the time to carry out different trials (repeat the experiment) and regardless, the sample sizes were too small to make any conclusions.  The activity provided me with a good understanding of what they understood about inquiry activities, however.

When a Science Experiment Fails: Signs of Fall

When An Experiment Fails

At the end of STEM Class a couple weeks ago, I attempted a little chemistry demonstration – just for fun.  I’d originally read about the pumpkin demo here, Rainbow Fire, and I did the experiment as described but as the kids can attest, it didn’t work. On the drive home, my kiddos hypothesized that the fact that I waited a little while for everyone to get settled may have caused the hand sanitizer to evaporate. Upon further investigation, however, perhaps I was missing a key chemical.  Another site I found, Green Fire, suggested the use of Heet (methanol).  A las, I will have to try again.   If any of you give this a try, please let me know what you discover. 🙂

The fact that it didn’t work out though is perfect science (though very embarrassing when done as a class demonstration).  When an experiment doesn’t go as planned, however hard to admit, it is actually great.  It gives you the chance to go back and really figure it out.  There is always an answer for why it didn’t work. You often learn more when it doesn’t go as planned.

Later that afternoon, Buddy was working on a aeronautics project (he’s trying to make an airplane with cardboard, rubber bands, and plastic propellers).  When his design doesn’t work out, he gets very frustrated and laments, “I wasted so much time on this! I wasted all this glue!” (or tape, or whatever materials he used). It is difficult to console him but with my own failure earlier that morning, I had an example with which to show it happens to all of us.

Recently, another activity seemingly failed and I thought I would share our process of discovery with you …

Signs of Fall

One of the extension activities I had suggested to my STEM students when we were covering plants was a chromatography activity to investigate the pigments in leaves, Signs of Fall (scroll down for the activity “Invisible Changes”).  Another link, with the same title, Signs of Fall, provides a PDF download for a student page with guiding observation questions.

My daughter and I worked together to set up the investigation just as it was described.  She was even careful to measure an exact amount of isopropyl alcohol into each jar. We then placed a strip of coffee filter into each jar, taping it into place to secure it and then capping each jar with a small piece of aluminum foil.  We left it over night but there was not a single strip with any color pigment.  We thereby walked away, shrugging our shoulders. Another failed experiment.  This was getting frustrating.

I couldn’t let this one go, however.  We must have overlooked something.  I thereby left it set up on the kitchen counter for another day or two while we contemplated and brainstormed what we might have done wrong. When we happened to peak into the jars a couple days later, we surmised that perhaps we had put the coffee strips into the jars too soon – before the heat of the water bath had had time to activate the pigments because the liquid in the jars was now clearly colored when before it had remained clear.

We thereby pulled off the aluminum foil, discarded our first strips and inserted new ones.  We checked the progress of our test a few hours later …

When a Science Experiment Fails: Signs of Fall @EvaVarga.netWhoa-lah! 

If chromatography is something you’d like to investigate further, you might also consider this activity, Rainbow Candies: A Candy Chromatography Experiment for Kids.  It is a great way to use up some of that leftover Halloween candy that may be laying about.

Life Logic: BotanyAn expanded version of this lesson is available in the Science Logic curriculum
Life Logic:  Plenty O’Plants.

What is Science? – Transitioning to Inquiry Based Instruction

Over the past few weeks I have been sharing with you a series of posts that address the scientific method, science process skills, and science as inquiry. Inquiry-based instruction often represents a new and complex classroom situation for teachers and students. Both need the time to gradually make a transition from the more classical type activities and lectures, to more open-ended activities characteristic of inquiry-based instruction.  Today, I share with you examples of how to easily modify existing cook-book activities for a more inquiry based instructional approach.

what is scienceA good place to start is to conceal the title of the activity.  Frequently the title of an activity can give away the instructional objective and students are thereby easily able to guess at an appropriate hypothesis.  Another suggestion is to remove premade data tables that accompany many lab activities. Have students figure out for themselves what data to record, and how to record it. While students may struggle and need assistance in the beginning, with continued practice they will find success.

Once students are comfortable recording their own data, educators can move on to further activity modifications. For example, parts of the procedures can be deleted. Students make decisions that can have small effects on the outcomes of the activities, while still using the materials the teacher had planned on using. Teachers can also experiment with having activities come before lectures (or direct instruction). This simple change can provide many wonderful opportunities for learning opportunities and discussions.

Example of a Classic “Hands-on” Science Activity

Make an Egg Float in Salt Water

An egg sinks to the bottom if you drop it into a glass of ordinary drinking water but what happens if you add salt? The results are very interesting and can teach you some fun facts about density.

What you’ll need:

  • One egg
  • Water
  • Salt
  • A tall drinking glass


  1. Pour water into the glass until it is about half full.
  2. Stir in lots of salt (about 6 tablespoons).
  3. Carefully pour in plain water until the glass is nearly full (be careful to not disturb or mix the salty water with the plain water).
  4. Gently lower the egg into the water and watch what happens.

What’s happening?

Salt water is denser than ordinary tap water, the denser the liquid the easier it is for an object to float in it. When you lower the egg into the liquid it drops through the normal tap water until it reaches the salty water, at this point the water is dense enough for the egg to float. If you were careful when you added the tap water to the salt water, they will not have mixed, enabling the egg to amazingly float in the middle of the glass.

Tweak it for Inquiry Based Instruction

Walking through the above activity step by step as described is a cook-book approach and while the child may find it interesting, there is little thinking involved.   Instead hand the student an egg and present them with an open-ended challenge, “I bet you can’t get this egg to float on water.”  Allow the child to work through their own ideas and solutions, offering suggestions or hints if necessary.

For more information on modifying science lessons and transitioning to inquiry based instruction, read the Science and Children article, This is Inquiry … Right?  (NSTA publication, Sept 2012).

My earlier posts in this series include:

What is Science? – The Importance of Inquiry

Earlier this month I shared with you my view that science is an exciting and dynamic process of discovery.  Today, I expand upon that definition to explore the importance of inquiry, specifically scientific inquiry.  The National Science Education Standards (NSES p. 23) defines scientific inquiry as “the diverse ways in which scientists study the natural world and propose explanations based on the evidence derived from their work. Scientific inquiry also refers to the  activities through which students develop knowledge and understanding of scientific ideas, as well as an understanding of how scientists study the natural world.”

what is science

Unfortunately, our traditional educational system has worked in a way that discourages the natural process of inquiry. Students become less prone to ask questions as they move through the grade levels. In traditional schools, students learn not to ask too many questions, instead to listen and repeat the expected answers.

In many classrooms and homeschool families, students enjoy fun science lessons that feature hands-on projects and activities that help bring the exciting world of science to life.  Unfortunately, many of these science experiences are canned lessons that do not require them to apply their skills and understanding of the scientific concepts.  Frequently, the experiments are laid out for them including the title, question, materials, and procedures.  While these technically “hands-on” activities are essential, they are not enough.  Students must also have “minds-on” experiences as well. Science is an active process, learning science is something that students should do, not something that is done to them.

Success in science is more than “science as process,” in which students learn such skills as observing, inferring, and experimenting.  Inquiry is central to science learning. When engaging in inquiry, students describe objects and events, ask questions, construct explanations, test those explanations against current scientific knowledge, and communicate their ideas to others. They identify their assumptions, use critical and logical thinking, and consider alternative explanations. In this way, students actively develop their understanding of science by combining scientific knowledge with reasoning and thinking skills.

importance of inquiry

The importance of inquiry does not imply that teachers should pursue a single approach to teaching science, nor a single curricula. Just as inquiry has many different facets, so teachers and home educators need to use many different strategies to develop their students’ understandings and abilities. The content can be organized and presented with many different emphases and perspectives in many different curricula.

Join me again in two weeks when I share with you examples of how to easily modify canned science activities to create inquiry based experiences.  I will provide examples of how teachers can move their classical instruction to an inquiry-based instructional approach.

My other posts in this series include:

What is Science? – The Process of Discovery

With the growth of social media, blogging, and the popularity of Pinterest, I frequently see science activities and lessons that parents, home educators, and teachers have pinned. While I love that social bookmarking sites have made science more accessible, I am frustrated with the cookbook approach and the growing misconceptions about what is science.

what is scienceOver the next few weeks, I will be sharing with you a series of posts that address the scientific method, science process skills, and science as inquiry.  Along the way, I will address several key misconceptions about science.  I look forward to engaging you in a dialogue – I hope you will join in on the discussion.

What is Science?

  • Focuses on the natural world
  • Aims to explain the natural world
  • Uses testable ideas
  • Relies on evidence
  • Involves the scientific community
  • Leads to ongoing research
  • Benefits from scientific behavior

Science is the human effort to understand, or to understand better, the history of the natural world and how the natural world works, with observable physical evidence as the basis of that understanding. It is done through observation of natural phenomena, and/or through experimentation that tries to simulate natural processes under controlled conditions.

For example, an ecologist observing the territorial behaviors of bluebirds and a geologist examining the distribution of fossils in an outcrop are scientists making observations in order to find patterns in natural phenomena. An astrophysicist photographing distant galaxies and a climatologist sifting data from weather balloons similarly are scientists making observations, but in private settings.

The above mentioned examples are observational science, but there is also experimental science. A chemist observing the rates of one chemical reaction at a variety of temperatures and a nuclear physicist recording the results of bombardment of a particular kind of matter with neutrons are scientists performing experiments to see what consistent patterns emerge. A biologist observing the reaction of a particular tissue to various stimulants is likewise experimenting to find patterns of behavior.

Common amongst each of these scenarios is that these scientists are making and recording observations of nature, or of simulations of nature, in order to learn more about how nature works.

How Science Works


Science is an exciting and dynamic process of discovery.  The chart illustrated above was developed by the University of California and the UC Museum of Paleontology, with funding by the National Science Foundation. The flowchart represents the process of scientific inquiry, through which we build our knowledge and understanding of the natural world. Most ideas take a serpentine path through the process, winding through process as shaped by unique people and events.

Exploration and Discovery

There are many routes into the process – like making a surprising observation in nature.

Testing Ideas

Testing ideas – in the field or in a lab setting – is at the heart of science.

Community Analysis & Feedback

Science relies on a community – within research groups and across all science disciplines.

Benefits & Outcomes

Science is intertwined with society and it affects our lives every day. 

Next week, I will explore in more detail the concept of scientific inquiry; addressing the misconception that there is a single scientific method that all scientists must follow.

Additional posts in this series include:

Exploring Death Valley National Park

The first park we visited during our 10-day road trip was Death Valley National Park on the border of California and Nevada in the eastern foothills of the Sierra Mountains.   Death Valley is a land of extremes and we enjoyed the contrasts.  Exploring Death Valley National Park led us to discoveries of Salt Creek pupfish, the mineral borax, and the historical meaning of the 20-mule team.  Today, I share with you a few of our discoveries at Death Vally and describe a fun science experiment you can do with your kids to explore the chemistry of borax. Devils Golf Course

It was evident that despite desolate appearances, Death Valley is one of the most impressive areas for birdwatching in the National Park System. There are several factors that result in Death Valley’s long bird list. As one travels from the low valley desert, up the canyons, through the pinyon-juniper woodlands and onto the high boreal peaks, climate and vegetation changes are obvious. This wide diversity of habitat leads to a high diversity of bird species.

yellow-headed blackbirdOne of our first adventures in Death Valley was the Salt Creek Trail.  It was here that we were able to observe the yellow-headed black bird for the first time.  We were surprised by his lack of timidity for he was only a few feet away from us and hopped about the raised pathway as we took the time to take his photograph.

Another marvel we enjoyed along this trail was the opportunity to observe the endemic Salt Creek pupfish (Cryprinodon salinus salinus). The pupfish of Salt Creek have a difficult life, but it was not always so. Ancestors of the Salt Creek pupfish lived in streams flowing into a huge freshwater lake that filled the bottom of Death Valley more than 10,000 years ago. Lake Manly, as it is known today, was the end of a drainage system that at the time included water from as far west as the Sierra Nevada Mountains. As the climate became more arid over time, the Ice Age lakes and rivers dried up and the pupfish were stranded in permanent water holes scattered across the desert.

Salt Creek pupfishToday, those isolated ‘islands’ of water vary drastically from freshwater warm springs and marshes to Salt Creek’s seasonal briny stream.  To survive in the different habitats, the original pupfish species evolved into ten distinctly different species, each with their own shape, markings, habits, and survival strategies.   Sweetie drew a pupfish in her journal as a part of the Junior Ranger Program.  We mailed our completed books to the park ranger upon our return home, however, as our travel plans did not permit us to return to the visitor center that day.

I like to call these specimens ‘pupfish’ because they play like puppies. ~ Dr. Carl Hubbs, father of Western ichthyology

In addition to the ecology of the valley, early settlers to this region took advantage of the areas rich natural resources. Stories of gold strikes in the newly acquired territory of California had been published in an official notice to Congress in 1848, sparking the California Gold Rush, enticing more than 250,000 people to join the search for riches over the next four years.  Mining continued in Death Valley for 150 years.

20 mule teamCrude shelters and tents once dotted the dry, flat lake bottom. Here, workers refined borax by separating the mineral from unwanted mud and salts, a simple but time-consuming process.  For more than a century, the 20 Mule Team has been the symbol of the borax industry.  The status is well-earned; mule teams helped solve the most difficult task that faced Death Valley borax operators – getting the product to market.  The teams covered 165 miles of forbidding terrain, traveling south through Death Valley, out Wingate Pass, then across the desert to Mojave.

The term  borax is used to refer both to a mineral and to a refined compound. The mineral takes the form of colorless to white soft crystals, which can sometimes have hints of brown, yellow, or green. The substance is also known as sodium tetra-borate and it has been known to humans for thousands of years. The mineral is a chemical compound of the element boron, and the chemical formula is Na2B4O7*10H2O.  A fun activity to try at home is to grow borax crystals in much the same way as you would make rock candy (sugar crystals).  It would also be interesting to research how borax has been used historically and how uses of varied between cultures.

Growing Borax Crystals

Growing borax crystals can teach many different chemical concepts, such as a saturated solution and crystallization.  The basic instructions for growing crystals are show here.  Using this as your control, you may consider varying the solution (what you dissolve the borax into) to see how it affects crystal growth.  Perhaps humidity and ambient temperature play a role in the growth of crystals? 

Materials Needed

  • wide-mouth glass jar
  • a pipe cleaner
  • pencil or chop stick
  • string
  • hot water
  • borax laundry booster


As you wait for the water to boil, bend a pipe cleaner into a desired shape (heart, star, circle, etc.).  Then tie a string around your pipe cleaner shape so that you can suspend it in your jar by tying the other end to a pencil or chop stick that will lie across the top of the jar.  Once the water is hot, fill the jar with it, measuring carefully to see how much water you use. For every cup of water, add three tablespoons of borax and stir well until it’s completely, or almost completely, dissolved. Suspend your pipe cleaner and leave overnight. Check it in the morning to see what grew.

Borax is a pretty common household substance and is thereby a great resource for different kinds of science projects. Borax is relatively safe and is very non-reactive, but it is toxic if swallowed, so it should not be used by very young children and it should not be used near food. It also can be irritating to skin and eyes, so you may wish to use regular household gloves when handling it and avoid getting it near your face.