Liquid Volume and Mass 3rd Grade

[Eric]

When looking at this 3.MD.2, it lists three specific units of measurement (g, kg, l).  Does this exclude other units of measure, such as cups/pints/quarts/gallons?  Usually if there’s more of an open interpretation the standard will say “e.g.”  However, this standard seems pretty specific on the units.  But then looking at the footnote, it prohibits using compound units such as cubic centimeters, which are same as mL (which isn’t listed in the standard).  Then looking at a “Common Core textbook” they take the liberty of including weight (ounces, pounds, tons) as well as mL.  I understand that the standards are not the “taught curriculum” but would like to know on what it would be fair to assess students?  When PARCC assesses these standards, will they be taking these liberties with the standards or taking the standards at face value?  Thank you!!

[Bill McCallum]

Well, we’ll have to wait and see about the assessments, but I hope they don’t take the same liberties as the textbook you cite. I don’t want to judge a book on hearsay, but there was a reason we limited the proliferation of units of measurement. There is much else going on in Grade 3 without carbo-loading on different types of units. Everything in its time, but not everything all at once.

[Eric]

Thank you, Bill!  My colleagues and I have had suspicions with these new textbooks taking liberties with the standards that we really don’t see.  I don’t want to use any names in this forum, but the one I’m talking about has a lot of “vision,” or so they say.  Other textbook studies I’ve seen only put textbooks as a mild to moderate fit for the Common Core.  Still a lot of the same stuff we’ve seen in past years.  Textbooks are wanting to give teachers “a lesson a day” to fill up the school year instead of giving them deep tasks that take days to finish and that require students to make sense of the mathematical content, developing fluency along the way.  Off my soapbox now.  Thank you again!

[carriew]

I do have a question about the units used in 3rd. I know, as Bill said, we need to stick to g, kg, and L, but how do children have a reference for liters? I know you can physically show them what a liter is, or examples of things that hold approximately one liter. What I mean is how do you assess that they know what a liter is when they have no liquid volume units to compare it to? Does this just involve comparing it to obvious things that aren’t near a liter like bath tubs, pools, or a spoon full of liquid?

There are no liquid volume units introduced in 2nd grade, and liter is the only one in 3rd. I know they aren’t supposed to be converting anything yet, but could you have them compare liters to pictorial representations of mL, cups, or gallons?

Thank you for any suggestions or advice! Just trying to be sure I’m interpreting this correctly!

Cheers!

Carrie

[Cathy Kessel]

Are you asking about the “estimate” in “Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l)”? I interpret this as being able to look at a bottle or other uncomplicated container (e.g., a glass), and be able to make a reasonable estimate its capacity in liters. (“Reasonable,” of course, is in the eye of the assessor.)

I don’t see that one needs another unit of measurement, for instance, I estimated the width of my hand was 4 inches (it’s actually more like 3.5 inches) so I have some sense of how long an inch is, even though I haven’t been doing a lot of length measurement.

[carriew]

Thanks Cathy, that makes sense!

As far as the measurements in liters, for having the kids actually do this in real life, is it okay for them to measure just 1 or 2 liters? Most containers I can find for liquid measurements only go up to 2 at the most.

Thanks again for the help! I appreciate it!

Cheers!
Carrie

[Cathy Kessel]

Do you mean that most containers for measuring (e.g., beakers with measurement scales) are only 1 or 2 liters? Students could manage to measure larger volumes if they used a third container for putting already measured amounts of liquid.

[carriew]

Yes, I just meant in a marked container for one measurement at a time. Thank you, Cathy!

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