Spring Scale Engineering 

Student Worksheet:

 Engineering Teamwork and Planning
You are part of a team of engineers given the challenge of building a spring scale to measure the weight of some items your teacher will provide you. In addition to a spring, you'll have lots of materials to use such as cardboard, wooden dowels, tape, foil, construction paper, glue, markers, string, rubber bands, wire, popsicle sticks, paper cups, straws, pipe cleaners, paper clips, screen, pvc piping, and other readily available materials.

 Planning and Design Phase
You may structure your scale any way you like, but must have a way of calibrating the scale so it will show a weight to you for whatever items you have to weigh. You'll want your scale to measure the weight of the items provided within 10% of the actual weight. You may want to test your scale with a range of items to make sure your scale works before classroom testing.  In the box below, draw a diagram of your planned scale, and include a list of the parts you think you might need.  You can adjust this later and also add more materials during construction.  

	
Materials List:

	
  Spring Scale Engineering 

Student Worksheet:

 Construction Phase
Build your scale and be sure to test it with several different items.  You'll want to see if your scale can distinguish between one golf ball and two, or one onion and two for example. Make any adjustments during construction that you like, including asking for additional materials you might need.  You can also trade materials with other student teams if they have extra items you need.

 Classroom Testing
Test your scale by weighing several different items at least two times each and record your results in the box below.  This will help you to test your scale 

For each item, record the mass of the item, the starting position of the spring based on your scale before you add the item to be weighted, and the ending position of the spring (after it is stretched).

Item you weighed	Mass (grams)	Starting Position (cm)	Stretched Position (cm)	Stretch (cm)	
Onion	 	 	 	 	
Ball	 	 	 	 	

 Evaluation 
Complete the evaluation questions below:

1. Was your scale able to measure the items provided by your teacher within 10% of the actual weight?  If not, how close was your scale and how did it compare with the results of other teams?

2. How similar was your original design to the actual scale you built?

  Spring Scale Engineering 

Student Worksheet:

3. If you found you needed to make changes during the construction phase, describe why
your team decided to make revisions.

4. Which scale in your class came the closest to the actual weight of the items provided by your teacher?  Was there something about the design of that scale or materials used that caused it to work the best?  Explain… 

5.  Do you think that this activity was more rewarding to do as a team, or would you have preferred to work alone on it? Why?  

6. If you could have used one additional material (tape, glue, wood sticks, foil -- as examples) which would you choose and why?

7. Do you think your scale would have been able to measure a weight of 600 grams?  Why or why not?

8.  What real world applications can you think of for a scale that is reasonably accurate but not absolutely accurate?

9.  Do you think that real engineers redesign their systems and products over and over during planning and manufacturing?  Why or why not?