Monday, March 30, 2015

Fantastic Foam Bridges - March 30, 2015

I do a lot of hands-on building projects because the students seem to enjoy them the most. This project is a variation on a marshmallow bridge project. This one is really exciting for the students because there's an element of competition, which brings and urgency into the situation.

 Supplies List:

  •     Foam cubes - it doesn't matter what the size is unless it's really small. 1 inch foam cubes work pretty well.
  •     Toothpicks
  •     Small cups to hold pennies (tiny cups you'd get from a dentist's office)
  •     Paper clips
  •     Pennies (up to 700 pennies)
  •     Plastic tub (to catch the pennies if/when the bridge collapses)
I draw a couple of truss bridge designs on a white board and talk about the triangles in the bridge design. Then I go on to talk about the advantages of using triangle; however, I caution them about the hypotenuse. With the toothpicks, the students have to do something about the length difference.

Project Instructions:

  1.     Hand out a tube of foam cubes and ~250 toothpicks to each team of students.
  2.     Build whatever shape the team wants to build.
  3.     Build, test, & build, again!
Here are some records to break for next year:

2nd graders - last year, 298 pennies
3rd graders - this year, 250 pennies
4th graders - this year, 450 pennies
5th graders - this year, 650 pennies

I don't have a lot of class pictures because I have to load the pennies very carefully, evening out the load on the bridge. So, the teachers take the pictures, but I haven't received the pictures, yet. So, here's what I have.

~150 pennies in the right and the left cups each

Try this one at home and have a wonderful time.

P.S. - The only problem with this project is that the foam cubes are quite expensive (between $17.95 - $24.95 per 102 cubes), and we can't keep reusing the foam cubes. So, it does get expensive for a class project when I try to collect $10/year/student for the science projects. If you know where I can get them cheaper, please let me know.

Thursday, March 12, 2015

Eerie Eye Tricks - March 12, 2015

This project is probably more appropriate for primary grades. I do have another eyes project for intermediate grades. I'll post that later.

Supplies List:
  • 6 to 8 pieces of 4in x 20in mylar (I found old calendars from RAFT and cut them into strips)
  • 2 x # of students in your class egg carton bottoms (the cup side) with holes (chopstick size) randomly poked out (don't you love how technically precise I get?)
  • A worksheet of up to 10 to 20 pictures of prey and predator animals (please include a picture of a baby and a Harper seal)
I start this project by talking about how the cells in our eyes are one of the oldest cells we have in our body. Then I quickly talk about cell renewal rates and the longest living cells, i.e. those that last a lifetime:

Here are some cell renewal rates of our body:
  • Red blood cells (erythrocytes): 120 days
  • Platelets: 10 days
  • Neutrophils (a type of white blood cell): 10 days
  • Fat cells (adipose cells): 8 years
  • Cells of the crypts in the colon: 7 days

The longest living cells, i.e. those that last a lifetime, are:

  • Neurons of the cerebral cortex 
  • Cells of the eye’s inner lens
  • Muscle cells of the heart
* All above info from Alaka Halder on Quora.

Then I go on to talk about why various creatures have eyes where they have - that eye location helped the creature best survive the environment in which it had to live. 

Humans have their eyes in the front. The binocular vision and depth perception are vital for an animal that swung through the trees. 

Prey animals have their eyes high and to the side of their heads. This grants them almost 360-degree view, as well as above their heads. They do have a small blind spot directly in front of their faces, but their keen sense of smell and big ears help them avoid their sight deficiency.

 Mylar Project Instructions:
  1. Hand out each strip of mylar to a pair of children. 
  2. Have the first child stand with a piece of mylar around his/her forehead height and bend it (not crease it, but rounded bend) to see the back of him/her.
  3. The second child will stand about 15 to 20 ft behind the first child.
  4. Then try to get the second child to sneak up to the first child successfully while the first child is looking into the mylar to check the safety of his/her surroundings.
  5. Do this a couple of times, then swap.
  6. You can do this with a group of children, and take turns until the whole class gets to try it.

*Sometimes it is quite difficult to see (for the children) if they don't get the angle right, but most should be able to do this.

I finish this section of the project with a question - would any of them like to trade their eyes for the mylar eyes (being able to see the side, top, back, etc.)? And why? You'd be amazed at what they come up with for wanting to trade or not trade their eyes. 

Egg Carton Project Instructions:
  1. Hand out two egg carton bottoms with a hole poked in them to each child. 
  2. Have them cover their eyes with the egg carton bottoms and see out the holes.
  3. Have them try several different locations (at the same time, i.e. a hole in left side might be pointed up and a hole in right side might be pointed to the side) and ask them to talk about or write down what they see.
  4.  Then I ask the children if anyone can tell me what creature has eyes like these?

I finish this section of the project with a question - would any of them like to trade their eyes for the egg carton eyes (being able to see two different locations, etc.)? And why? Again, you'd be amazed at what they come up with for wanting to trade or not trade their eyes. 

Then I go on to talk about how just by looking at the eye location, we can guess whether the animals are prey or predator animals.

Animal pictures worksheet Instructions:
  1. If eyes are in the front, they belong to a predator.
  2. If eyes are on the side and high on the animal's head, they belong to a prey.
  3. With pictures of babies and Harper seals, the children get confused. This is another point of discussion.
Again, lower grades seem to enjoy this much more than higher grades, but I've done this with 4th and 5th grades with additional invisibility elements to the lesson. This will follow next (I'll try for next week, but I'm not sure). 

Have fun!