Category: Fun Science Activity (Page 100 of 112)

Weekend Science Fun: Insect Mouthparts

While preparing for Thanksgiving, I realized the turkey baster was missing from the kitchen. I knew exactly where it was, however. It was in the bin where I keep all my insect teaching demonstrations. It turns out that a turkey baster is a great tool to show how certain types of insect mouthparts work. That gave me an idea for some weekend science fun that is quick, easy and educational.

Remember the discussion in the cochineal scale post about whether they were scales or beetles, and how different insects possess different types of mouthparts? Studying insect mouthparts can help not only with identification, but also to further understand the insect’s biology.

Gather:

  • Enlarged photographs of insect heads showing mouthparts (nature calendars work well) or large plastic insect models
  • Pliers, gardening shears or scissors (as an example of chewing mouthparts)
  • Turkey baster (as an example of sucking mouthparts)
  • Boxed drink with straws still in the wrapper (as an example of piercing/sucking mouthparts)
  • Party favor and drinking straw (as an example of siphoning mouthparts)
  • Sponge (as an example of sponging mouthparts)
  • Few tablespoons of baking powder
  • Small container of water
  • Plant leaves (optional)

Chewing Mouthparts – Mandibles
Common insects such as beetles, grasshoppers and caterpillars have mouthparts that are like pruning shears. The jaws, called mandibles, are cutting blades that move from side to side. You can show this by cutting a hole in a plant leaf with pruning shears or scissors.

model insectmodel insect

Dr. George Butler made this model of a grasshopper head for me about 15 years ago. The insect’s upper ‘lip’ (that covers the mandibles) is hinged, so it can be pulled up to show the white mandibles underneath. Under the mandibles are the maxillae, which have finger-like projections called palps. The palps taste and move around the food. The lower ‘lip’ also has palps. It is called the labium. Who knew an insect mouth would be so complicated?

For younger children, a pair of plastic pliers can be a safe and easy example of how mandibles work.

model insect

There was a beetle in the picture too. This is what happened to it 🙂

cat eating beetle

Piercing/sucking Mouthparts – called a Proboscis
A large group of insects, such as mosquitoes, stink bugs and cicadas have mouthparts like tubes that pierce into their food source and suck up the juices.

insect

This is a model of a cicada head.

Some sucking mouthparts are like the turkey baster, but most sucking mouthparts are not simply tubes. They consist of a sheath or wrapper around a bundle of structures called stylets.

model insect

Insert two box drink straws into one wrapper, with the bottom open. Then punch the straws into the drink. You will see that the wrapper folds back the way a sheath would in an insect proboscis. The fluid would flow up not just within the straws, but between them as well.

model insect

Siphoning Mouthparts
Adult butterflies and moths have siphoning mouthparts that are simply a flexible tube that they slip into fluids, like nectar. When not in use the tube rolls up like a party favor.

model insect

model insectmodel insect

Sponging Mouthparts
Certain types of flies have mouthparts that are like bits of sponge. In a fun demonstration, sprinkle some baking powder on a plate or table surface. Explain that this represents some food like sugar that a fly might want to eat.

model insect

Ask the children to try to “eat’ it with a piece of dry sponge. It doesn’t work too well. Ask them how the fly might make it work better. Usually someone gets the idea to wet it. Pour a bit of water on the powder (I use baking powder because it fizzes a bit adding to the drama). Explain that a fly actually ‘spits’ on its food to wet it. Now the sponge can suck up the food easily.

model insect

Mixed Mouthparts – For example, the Honey Bees

Not all insects have just one type of mouthpart. For example, honey bees have two types, mandibles and a proboscis. The mandibles are used for any chores about the hive that require grasping or cutting, such as working wax to construct the comb, biting into flower parts (anthers) to release pollen, carrying detritus out of the hive, or gripping enemies during nest defense.

The proboscis of the honey bee is simply a long, slender, hairy tongue that acts as a straw to bring the liquid food (nectar, honey and water) to the mouth. The sheath in this case is called the stipes. When in use, the tongue moves rapidly back and forth while the flexible tip performs a lapping motion. After feeding, the proboscis is drawn up and folded behind the head.

honey bee head

The study of insect mouthparts isn’t just for kids.  In depth discussion of insect mouthparts can be found at the  University of Kentucky Master Gardener Website

While you are at the University of Kentucky, they have a whole bunch of information about insects and activities for kids, starting at this link:
Kids Home University of Kentucky

Weekend Science Fun: Growing Crystals

Growing crystals can be fun because crystals grow and change in amazing ways and they can be incredibly beautiful. At times growing crystals can be frustrating because it may demand unusual and potentially hazardous materials, because it can requires patience when the crystals take a long period of time to grow, and because there is no guarantee of success. In fact, I was inspired to look into growing crystals because someone else had difficulty growing sugar crystals and wanted to know why. Do give it a try, however, because often you can learn more about science from the projects that didn’t work out as you planned than from those that turn out picture perfect. And once you are successful, crystals are awesome!

What are crystals? A crystal is a solid material that has its atoms or molecules arranged in a regular, repeating pattern. This causes the crystal to be symmetrical, and leads to many fascinating geometric shapes. For example, some form cube shapes, like table salt. Others form hexagonal shapes, like six-sided snowflakes.

If you get a chance, look at table salt or a snowflake under a hand lens or microscope. To catch a snowflake, put your hand in a dark (black works best) sock or dark, plain-colored mitten and allow snowflakes to fall on it.

Here are some photographs of naturally occurring crystals. This is rock salt, sometimes used for making homemade ice cream.

rock salt

This is a geode. A geode comes from gas pockets that formed in magma when it cooled. The crystals can grow slowly within the protected pocket, reaching their full potential shape.

geode

Let’s try a few crystal-growing experiments. They will almost all require an adult’s help.

1.    Growing Salt Crystals -fairly easy
Gather:

  • Drinking glass or small, clear glass jar
  • Hot water (requires adult help)
  • Table salt and Tablespoon size measuring spoon
  • Nail
  • Pencil
  • String

Fill the glass or jar about ¾ way full. Start adding salt to the water one tablespoon at a time. Stir after each addition until the salt dissolves. Keep adding salt until a bit remains undissolved. This is a saturated solution.

Now, tie one end of the string around the nail and drop the nail into the solution suspended by the string. Lay the pencil across the top of the glass or jar and tie the other end of the string around it. The nail is a weight to keep the string straight in the water, supported by the pencil.
Now it is time to wait. Over the next few days the solution should dry and leave salt crystals on the string.

2. Grow Ice Crystals – a Snowy Day Project
Gather:

  • A drinking glass or clear jar
  • Enough snow or frost from the freezer compartment of the fridge to fill the glass half way
  • Table salt and Tablespoon size measuring spoon
  • Small test tube
  • Water

Fill the glass half way with snow or powdered frost. Press down to compress. Add one Tablespoon of table salt. Now fill the bottom of the test tube with one inch of water. Place the test tube into the snow mixture. The snow and salt should start to melt, and at the same time the water in the test tube should start to freeze into ice crystals. Add more salt to the snow and swirl a bit to mix if things aren’t progressing.

3.    Sugar -Rocky Candy Crystals – A bit more detailed

The person who had trouble with the sugar crystals tried using the same method as the salt crystals above. She added sugar to hot water until it was saturated and then let it dry on a string. Making a sugar syrup by boiling the sugar in the water, and seeding the string with some dry sugar crystals works better. See the instructions for making rock candy at  About. Com.

4. Almost everyone has tried or seen the crystal gardens that use laundry bluing and ammonia. Both these ingredients need to been handled with caution.

Gather:

  • 2 Tablespoons table salt
  • 2 Tablespoons laundry bluing (available in the laundry section, read the warnings on the label first)
  • 2 Tablespoons household ammonia (read the warnings on the label first)
  • 2 Tablespoons water
  • disposable aluminum dish
  • Food coloring (optional)

Check the bluing bottle, it may have a recipe for a crystal garden on the side which you could use, as well. Otherwise, simply mix the ingredients in a disposable aluminum container. In the video below a cardboard toilet tissue was placed upright in the dish. Note:  you will see that strips have been cut in the top of the roll. Those were actually supposed to go into the liquid to help wick up the solution. Obviously it worked quite well anyway.

You can also pour the liquid over pieces of coal or even bits of clean, dry sponge.

Growing Salt Crystal Garden Video

You can grow crystals from kits as well. This example is aluminum potassium sulfate crystals grown on a granite base.

crystal

If you grow a cool crystal, be sure to take a picture, load it on a blog or website and send me the link. I look forward to seeing them.

For more information, ideas and links visit the crystal projects for kids page at About.com.

You can also buy kits (check customer reviews, images are affiliate links to Amazon)

Smithsonian Crystal Growing Kit

Amethyst and Diamond Crystal Growing Kit

Crystal Growing Tree

 

Weekend Science Fun: Why Do Apples and Pumpkins Float?

One question that has come up (pun intended) from previous posts in this blog is why do pumpkins and apples float? To answer this question, we first need to look at why things float in general.

Do you still have your bin of water? Let’s try floating a few more things.

People have been wondering why things float since olden times. According to legends the ancient Greek, Archimedes, conducted experiments to test why things float or sink. Supposedly he figured it all out while sitting in the bathtub. Our modern interpretation is called Archimedes’ Principle.  It states that a body floating in a fluid is supported (or buoyed up) by a force equal to the weight of the fluid it displaces.

Let’s choose water as our fluid. Do you know how much a cubic centimeter of water weighs? How about a gallon?

A cubic centimeter of water weighs 1 gram by definition. A gallon of water (at a given temperature of 4 degrees C) weighs 8.34 pounds. So, in order to float, an item that weighs 1 gram must displace more than a cubic centimeter of water. An item that weighs 8.34 pounds must displace more than a gallon of water to float.

To test this, obtain a piece of modeling clay. Shape it into roughly a cubic centimeter. See if it will float. It will probably look something like this:

sunk

(Clay at the bottom).

Now, flatten out the same piece of clay and make a boat shape. A flat bottom with a lip around the edge works well. Place it onto the surface of the water. It should displace a lot more water this time and float. Although the weight of the clay didn’t change, the amount of water displaced did change.

float

Have you tried floating a can of diet soda versus a can of regular soda? Both are the same size and shape, will they both act the same when placed in water?

Here’s a silent video demonstration.

Why don’t the two identical objects act the same way? According to the box at the bottom of this How Stuff Works page, diet soda has less sweeteners added, so it actually weighs slightly less for the same volume than regular soda. Because they are both mostly water, that slight change is enough to allow diet soda to float. Cool!

Apples and pumpkins are not solid. The pumpkin has a large hollow inside. Both weigh less than the amount of water they displace, and thus they float.

Try floating pumpkin seeds. What about apple seeds? Do they float?

We found that pumpkin seeds floated, but apple seeds did not. The pumpkin seeds are flat and displace an amount of water roughly equal to their size. On the other hand, apple seeds are compact and round. They displace little water. They don’t have to be very heavy to sink.

A few years ago, our family participated in a contest to build a working boat out of cardboard. We started by investigating various boat designs and materials by floating models in a tub. We learned a lot about sinking and floating. You might want to make some paper boats and try them yourself.

Enjoy!

Instructions to make a Classic paper boat

Another cool design for a paper boat that works well.

Edit: check out this video of a huge pumpkin made into a boat.

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