BACKGROUND:

Real objects aren't always a perfect shape.  In order to describe such objects, one must be able to make a "close approximation."  Sometimes the endings -ish or -like can help distinguish a perfect shape from a not-so-perfect shape.  For example, a roundish object or a square-like shape.

In this lab, students will look at different objects.  They will describe their shape and color.  Students will predict and record the measurements of objects before they measure them.  The metric system is recommended because it is easier to measure a fractional part of the object.  Even if students have not learned about decimal points, it is easy to say centimeters before the decimal, millimeters after the decimal.  The English system is difficult to convert because the decimal system basically converts the English system to metric.  Using metric to start with avoids the use of conversion.

 

PROCEDURE:

1. Pass out the objects.  Tell students that they need to describe the shape and color(s) of each object.  Model how to do this with one student's object.  After recording the shape and color, they need to predict the object's  dimensions.  In most cases they need to only guess at it's length and width.  Occasionally they also need to mention it's height.  Remind them that their guesses will not be held against them if they are wrong.  The more they practice measuring the better their guessing will become. 
   
   Reinforce the difference between length, width, and heigh.  Demonstrate how to measure an irregular object like the abalone shell.  Length is the longest length and width the shortest. 
     
2. After they have predicted the dimensions they can use a metric ruler to measure the  object. Ask them to record their measurements in the spaces provided and compare it with their prediction.
     
3. The information below will help you with each of the items.
   
   CUBE WITH MAGNIFYING LENS: Students should predict the length, width, and height. As an extension, you might want students to describe the magnification, which is approximately 2 times.  Students can find the magnification by putting a line on a piece of paper.  Next, put the magnifier over the line and draw the apparent height they see and then compare.
     
   ABALONE SHELL:  Students should count the number of holes, length, and color on one side and the other side.   The holes are used by the abalone as a way to get water through its body.  Remember abalone only have one shell.
     
   SCALLOP: Students should measure the length and width and describe the shape.  Remember that the length is the direction in which it is the longest.  The width is the other direction, and the “fattest” portion of the width, is the actual number.
     
   SNAIL: Students should measure the length and width, and describe the color.  The geometry of the snail is “spiral.”
   
   SEA URCHIN SPINE: Students should measure the width and length of this sea urchin spine, which was attached to a sea urchin when it was alive.  The spines would radiate from the sea urchin body, and helps the sea urchin move.  Many times people use the spines in necklaces.
     
   FLOWER CORAL: Students should measure the width and length and describe the color.  This specimen represents on coral individual.  The living animal had tentacles that trap particles in the water from which it finds food.
     
   LEAF: Students should describe the length and width and describe color.  You may want to replace this with a real leaf.  If possible, use real leaves so students can also describe the veins.
     
   ANIMAL SHAPE: Describe the shape and measure length and width.  Have students describe without mentioning the name of the animal.  This is difficult. 

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