The Nervous System

5th Graders explored the Nervous System today!

Neurons are specialized cells that use electricity to send messages to and from the brain.

Neuron by Andrew

Neurons transmit messages to each other using chemicals and electricity.  There are sensors (nerves) in you hands, feet, mouth, ears, eyes and nose that send your body messages from your surroundings.  Your brain interprets these messages to help you react (by sending messages from your brain through your spinal chord (bundles of neurons) to your muscles.)

Check out this video by Schoolhouse Rock for a broad overview of the nervous system.

Today we used our sense of touch to trick our nervous system.  After we put one finger in hot water and one finger in cold water, we put both in room temperature water.  The water felt cold to one finger and warm to the other!

One finger in hot water, one in cold.

The room temperature felt hot to the cold finger and cold to the hot finger!

Then, I played a trick on students' senses.  They tasted 4 different liquids each with just a hint of flavor and then had to guess what each flavor was.

After tasting each, most guessed cherry for red, lime for green, lemon for yellow, grape for purple. 

Turns out they were all the same flavor, berry!  Sensory input from our eyes can be interpreted incorrectly in our brain because we usually associate different flavors with certain colors.

You use different parts of your brain for different activities.  Many of us have a dominant side (left or right brained.)  Your left side is responsible for logical thinking and reasoning.  Your right side is responsible for creativity.   Which way does the cat move, clockwise or counter clockwise.

 If the cat moves clockwise you are more right brained and if you see the cat turning counter clockwise you are more left brained.  Some can even switch directions!

World of Color for Smiley Faced Kindergarten

A class of Kindergartener's earned 100 smiley faces for good behavior and chose the science lab as their prize.  As a result, I got to see 28 smiley faces in my lab today!

Color is a physical property we can use to classify objects into groups.

Sometimes scientists have a hard time classifying things if they don't quite fit into categories.  Scientists put a platypus into the mammal category, but it has a bill and lays eggs!  We found objects like that as well.  How would you classify this?

                                  The platypus of color!

The primary colors (needed to make all the other colors) are RED, BLUE, and YELLOW.  We did a little color mixing to test this out!

We set 3 primary colored water cups next to each other.

 

 

 We connected them with paper towels.

 

 The water absorbed through the paper towels.

 

 

We left them overnight and they mixed in the empty cups and formed purple and green!

 

We also created a glue color creation with watered down glue, food coloring and a stick dipped in soap.

 

Check out our creations!

 

Then we created secondary colors (green, orange and purple) from primary colors in our test tubes.

 

 

We also found that black contains all the colors, and....it is possible to separate them!

Black ink finger print on a coffee filter.  Dip the bottom in a little water and voilà, primary colors!

 

 

Separated colors on the coffee filter.

Lastly we talked about white light containing all the colors of the rainbow!  We used CD's, special glasses and bubbles to break up the white light into colors!

 

We took a picture through the glasses and this is what it looked like.

 

 

Check out a favorite story book, Little Blue and Little Yellow by Leo Leoni displayed as a stop animation created by Lauren Chartuk.


Check out this experiment from Steve Spangler and try this at home!

Transportation in Plants

Just like our blood moves necessary substances through us, plants have a system to do that too!

The plant needs water and minerals which are absorbed through the roots. There are tubes in the roots, stem and leaves that are responsible for carrying water.  These are called xylem.


Hitting a xylophone with water tube to remember xylem carries the water!


The plant makes its food (glucose) in the leaves and needs to transport it other parts of the plant.  To transport food the plant uses a different set of tubes called phloem.

 (I think phloem for phood- yes I know you spell it food, but I know you'll remember how to spell food!) Check out this student drawing of the process.

 

 

Today we looked at the xylem tubes in celery.  After putting the plant in colored water for an hour, we could see the color travel up the stem into the leaves. 

 

We even took a xylem tube out for further exploration.

 

Plants are able to transport water because water has some special properties.  It is a polar molecule!  This creates surface tension caused by adhesion and cohesion.  Adhesion is water sticking slightly to other objects, like your finger (seeming to defy gravity.)

 
 
Cohesion is when water sticks to itself (try playing with a few drops on wax paper.)  Or check out this "skin" created on top of a graduated cylinder.

This causes capillary action, that is the tendency of water to rise in a small tube.  The water sticks to the tube and the molecules stick to each other.

When the plant is losing water through the leaves during photosynthesis, more water is pulled up from the roots in the xylem tubes using capillary action.

We mad a model plant to show the pull of water.  The capillary action moved the water up the "plant" and through the "leaf" (also separating the color black we put on the coffee filter "leaf.")

 

 

 

 

Check out a virtual transpiration lab on your own from Glenco/McGraw Hill.

virtual lab

Convection Currents

5th Graders studied and created convection currents today.

Convection currents occur when there are differences in density.  Most of the time this is caused by heat changing the density of a substance. 

When a substance gets hot, the molecules start moving faster and spread out.  The substance becomes less dense and rises.  When it rises away from the heat, it cools.  Then it falls back down where it is heated once again.  This is an example of a convection current.

Convection currents occur everywhere!  In the air (sea and land breezes are perfect examples), in the earth's crust (that is what makes plates move), and in the ocean when warm water or less salty water rises.

Before creating our convection current, we were reminded about density while making a puddle out of different temperatures of water.

First we poured in our yellow room temperature water.

Not really that exciting.

Next, we poured blue cold water in!   We remembered that cold water is more dense than room temperature water, so we predicted it would sink to the bottom. 

It looked a lot like the cold front we created only different colors!

Lastly, we poured our red, hot water down.  Remembering that hot water is less dense, we predicted it would be on top.

It was!

After cleaning up our rainbow puddle, it was time to put our knowledge to the test.  We started with a tub full of room temperature water.  We took a few drops food coloring and put it on the bottom of the tub.  Then we created a hot spot underneath the food coloring. 

 

Voilà, a convection current!  The hot water heated the spot with the food coloring, causing the water to rise (and the food coloring).  When water hit the top it moved to the sides, cooled and came back down. 

Check out these videos. 

This first one is from Eureka!  They have some great science videos for your curious brain!

This one is from Glaskar and Mega Systems and explains how convection currents work inside the earth to move plates.

 

Changing Salt Water into Fresh Water

Today 5th Graders used their knowledge of the water cycle to create a device that changes salt water into fresh water.

Most of the earth's water is trapped in the ocean.  It is not useable for drinking.  In fact if all the water in the world was modeled by a two liter bottle (2000 mL), 1950 mL would be salt water!

Only 50 mL would be fresh.  This fresh water includes unreachable ground water, lakes, rivers, and streams, as well as glaciers and ice caps.

Taking away all of the unreachable water (in the ice caps and deep underground or trapped in porous rocks) only .5mL of our model would be drinkable water!  Amazing we don't die of thirst!

Today students worked in groups to design a way to turn salt water into fresh water using their knowledge of some very important water cycle words!

Evaporation:  When liquid water turns into a gas and rises.
Water must evaporate out of the salt water, leaving the salt behind.

Condensation:  When water vapor turns into liquid water.
The water vapor must condense to form liquid fresh water.

Precipitation: Water falling in any form.
The condensed water must fall (into a new container hopefully).  The collected precipitation should be your fresh water.

Check out these contraptions:

I think I would want these kids with me on a deserted island!

We also used our knowledge of the water cycle to make  a cloud.

The water cycle

First we evaporated hot water.

Then we put dust in for water to stick to.

Then we cooled the water by putting ice on top.  This caused condensation onto the dust particles and the bottom of the cup.

Then we watched the cloud form in the jar.  The cup and jar began to precipitate!

Of course we had to let the cloud loose and enjoyed watching it rise out of the jar.

Check out another way to make a cloud.  This time I used rubbing alcohol and air pressure changes to create a cloud.

Think about why it works.

This cloud is made by changing the pressure!  When you change pressure you change the temperature.  High pressure- higher temperature.  When I untwist the bottle, I lower the temperature and cause the water to condense on the rubbing alcohol fumes. With a parent, see if you can get the same result!

 (Blue food coloring is in the alcohol so you can see it better.)

This is a great silly science song about the water cycle

Water Cycle by Mr. Davies on School Tube

Electromagnetism

Electricity and Magnetism have quite a bit in common.  Opposites attracting, likes repelling.  Both have an area around them called a field.  Up until Hans Christian Oersted, these two forces were thought to be similar, but separate.

On April 28, 1820 Hans Christian Oersted made an amazing discovery as he was giving a class lecture (if I could be so lucky!)  He happened to have a compass on the demonstration table he was using for his circuit demonstration.  When he closed the switch, the compass needle moved!  

Electricity produced a magnetic field! Whoa!

Check out the picture from How Stuff Works.

This was the birth of the electromagnet.  Or a magnet you can turn off and on  (I like to picture a big crane lifting cars.)

We build an electromagnet in the lab today and discovered ways to make it stronger.

After experimenting with different variables we found two ways to make it stronger.

There are electromagnets in all kinds of devices, you ipod, buzzers, bells, microphones, even toasters!  Below is an image from Wikimedia.

This bell works using an electromagnet.  The current flows around the upside down u shaped piece of metal.  This makes the u into a magnet.  The u attracts the metal below causing the ball to hit the bell.  When this happens, the circuit is broken and the U is no longer magnetic.  The ball falls.  The circuit is connected again and the whole processes starts again.

The amazing part is that a magnet can also produce electricity!  Double Whoa!

This is how we get electricity today!  

By moving wires or magnets next to each other, a current is produced.  You can use a variety of ways to turn the wire or magnets (wind, water, steam produced by burning fossil fuels.)

Check out this coal generator process from Footprints Science.

Coal generator

Or even build you own!

Build and electromagnet