Mass/Weight/Data/Graphing - "WHAT IS THE MASS OF A DINOSAUR?"

Alan Tobecksen                 Fenger HS
                               11220 S. Wallace
                               Chicago, IL 60628
                               (312) 821-4306

Objectives:

1. Students will learn the difference between mass and weight.
2. Students will practice using the triple-beam balance.
3. Students will gather data in an orderly manner.
4. Students will use their data to make a histogram (bar graph).

Materials Needed:

1. Balances
2. Weighted "eggs"
3. Long piece of paper
4. Markers

Strategy:

Use an attention-getter as a "hook."  I use "Chinese Sticks" - a small toy which 
consists of 2 hollow tubes with a sliding weight in each one and a string 
attached to the weight.  You start with one string pulled out (which pulls the 
weight to the top) and the other string in.  You pull the string and at the same 
time tilt the sticks (so that the weight at the top slides down and pulls the 
string with it).  It appears to the students that the strings are connected 
somehow and they are amazed when you pull the sticks apart and show that there 
is no connection.  It often takes a long time for someone to figure out that 
gravity is what controls the toy.  If someone does figure it out, it is a 
perfect lead-in to the experiment. 

What is the mass of a dinosaur?  In each "egg" there may be any number of 
dinosaurs from 1 to 11.  The mass of each dinosaur is about the same.  Students, 
in teams of two or three, weigh "dinosaur eggs", record the weights in an  
orderly manner (of their own devising), then take their data and transfer it to 
a bar graph.  Students should see a pattern emerge of a difference of about 50 
grams between eggs. 

This is a beginning of the year experiment and many students really do not know 
how to use a balance, do not know how to gather data and do not know how to make 
any kind of a graph.  Students can learn from each other and, if necessary, the
teacher can guide them. 

Construction of "Dinosaur Eggs":

Get about 100 L'Eggs containers or any egg-shaped container.  Use anything handy 
to add mass (I used nails, screws, lead shot, ball bearings, wire scraps, etc).
I constructed eggs with masses of 75g, 125g, 175g, 225g, 275g, 325, 375, 425g, 
475g, 525g, 575g.  I then sealed the eggs with a small strip of gray tape.