Density and Measuring

Density and measuring

"What are we doing to help kids achieve?"

     If you are looking for a measuring and density activity that will be challenging, allow students to experience success early on and can be boxed up to use again, you might consider trying the activity that I am sharing in this post.  

     Students just finished work on measuring. I wanted an activity where they had to put their measuring skills into pratice. The activity developed into one in which they immediately know if they measured correctly. The objects they measure are five pieces of polymer clay.  Polymer clay is a relatively inexpensive material that can be molded easily and baked in the oven. The final product are plastic-like pieces. The five pieces in each lab set are different shapes, sizes, mass and different markings. Each group gets a different color. One of the five pieces of clay has metal shot (lead works well) embedded inside it. Students are not allowed to break open or destroy the clay pieces. Students are told that somehow they must determine which of the five pieces has been tampered with and is not pure clay. 

     The class spends time brainstorming. The brainstorming session usually leads to determining the density of each piece. The density is usually found by getting the volume through water displacement and then finding the mass. The water displacement is familier to some students but not all. If students do not carefully measure to the correct significant figures then they will struggle with determining the correct "tampered" piece.

     This activity for me as a teacher has morphed over the years. The activity lends itself well to differentiation. Some classes are given more or less information depending on the level of the class. The class can also be given "distractors" (What is this funnel for ?). The students in the class can get instant feedback. The student's success depends more on an actual action and less about "Did I get the right answer on my paper?".  It is appropriate for most student skill levels at this time of the year. Students are also provided the option of doing a retake if they did not identify the correct piece.

     There are many density and measuring activities to choose from. This is a nice one with little prep time (after the initial creation of the pieces). The activity can be boxed and done year after year and changed depending on the level of students. Do you have a similar activity? Please share...would love to hear from you.

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Comments 7

Ben Meacham's picture
Ben Meacham | Tue, 09/05/2017 - 19:39

Very cool!  This may be a silly question but does that mean the polymor clay does NOT retain water?  I'm just thinking of situations where I've used wet clay before and the water retained clearly caused an increase in mass.  

I might be making a late night Michaels run to buy me some polymer clay!

Chad Husting's picture
Chad Husting | Thu, 09/07/2017 - 09:36

Ben - Once the clay is cooked it acts and feels like plastic and is water resistant.  Hope this helps.

Amiee Modic | Wed, 09/06/2017 - 12:39

VERY cool idea Chad! I want to try it next year (we already have something going on with density this year). Did you dry the clay pieces so they weren't tempted to search for the lead shot? Maybe I missed that part. #hurricaneharveyheadache

Chad Husting's picture
Chad Husting | Thu, 09/07/2017 - 09:38

I made 5 pieces of different sizes.  In one piece I placed lead shot in the center.  I then baked it based on the instructions.  Students saw 5 pieces that were differenct shapes and sizes and felt like plastic.  They were not able to see the lead and they could not break it open (or they would lose points).  Hope this helps.

Amiee Modic | Tue, 09/12/2017 - 10:59

Thanks Chad, I assumed you needed to bake it but wanted to be sure. I love this idea. Simple, discrepant, done!

Cindy Skarda | Fri, 09/22/2017 - 09:00

This sounds like a great idea for my students, what type of lead shot do you use? Fishing weight or other? how much do you use. Thanks

Chad Husting's picture
Chad Husting | Sat, 09/23/2017 - 19:41

Cindy - First I had some lead BB's.  I used as many as I could get in the clay but I still wanted the clay pieces slender enough to get in a graduated cylinder.  I also had some lead plate that I could cut.  I think lead sinkers would work.  I used the lead that I had in the storeroom.  I would first start with one set of clay pieces and place as much lead in one piece as possible and then check the density for all 5 with the same equipment the students would use.  Hope this helps.  Thanks for the comment.