Converting Weight using Metric System

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The students will be able to convert measurements of weight within the Metric System.

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15 minutes

Today’s lesson focuses on converting weights within the Metric System.  Students measure the weight of various objects around the room using gram spring scales.  They then convert these measurements into other units within the Metric System.  During the second part of the lesson students will be practicing converting amongst all the units of Metric weight.  The lesson will end with an exit slip to check for understanding that includes three real-world story problems involving converting weight in the Metric system.

To begin this lesson I provide students with an index card and then show them how to use a spring scale.  I have students set up a four column chart on the lined side of the index card.  I explain that they will be measuring the weight of various objects around the room.

Today we are going to be measuring the weight of objects around the room using the metric system.  What units of measurement did we use in the U.S. Customary system?  What unit are we going to use in the metric system?  Can you think of some other units of grams? 

The spring scales we are going to use today will help us measure things in grams.  We won’t be able to measure things that are super heavy or super lightweight.  When you choose objects keep that in mind. 

On your index card you are going to write down five items that you and your partner are going to weigh.  The name of the object goes in the first column.  In the second column put the weight in grams.  For now, leave the other two columns blank. 

Most of the time when everyday objects are weighed we see the measurements in kg, g, or mg.  So for our conversions today we will focus on converting our gram measurements to kilograms and milligrams. 

Once students have finished measuring their five objects we move back to our seats and then I start to model conversions for students.  I call on students to share their objects and then go through the process of showing how we convert from grams to kilograms and then from grams to milligrams. 

After doing a few examples with students I have them finish converting the remaining objects on their cards using the blank columns.  I then call on students to come up to the document camera and present their conversions for their one of their objects.  For example, my penciled weighed 6 grams.  6 grams is equivalent to 6000mg which is equivalent to 0.006 kg.


30 minutes

After modeling for the students how to do conversions of grams I now have students work in pairs to complete a skills sheet for today.  I allow the students about twenty minutes to complete the conversions while I circulate the room and support students.  I target students who struggled on their exit slip from yesterday.

At the end I display the correct answers on the document camera and allow students to self-correct their work.  After a few minutes I ask students to share examples of what they did wrong on problems they did not get correct.  My goal is that students are able to reason through the problem and identify where they got off track. 

I think that if one student struggled with a certain problem, another student probably struggled with the same problem.  It is good to have the student reason through their mistakes to make changes in their thought process.

We then add grams to the graphic organizer under metric weight. 


15 minutes

To wrap up this lesson I have students complete an exit ticket which includes three story problems I created involving converting weight units.  I use this information to guide me in deciding if further clarification is needed in converting weight in the Metric System.  I look to see where students struggled to pin point exactly what part of converting is unclear to them.