5.MD.A.1

Viewing 6 posts - 1 through 6 (of 6 total)
  • Author
    Posts
  • #1965
    Tracy
    Participant

    Is the conversion between units only inclusive of metric and US Customary or does this standard also include time?

    #1970
    Jason Zimba
    Participant

    I’ll try to offer some thoughts here and I hope they’re helpful – although I’m not sure what is meant by “the metric system.” The system of units that is used for scientific purposes is the SI system.

    Time is one of the base quantities in the SI system. The SI unit of time is the second. Minutes, hours, and days are outside of SI, but these units are accepted for use within SI. (Information about the SI system is found here.)

    If you look in the previous grade, you’ll see that standard 4.MD.1 is explicit about hours, minutes, and seconds. So it would certainly be natural for hours, minutes, and seconds to be part of the continuing thread in grade 5.

    (It is often helpful to look at progressions across grades in order to shed light on a specific standard within a single grade.)

    I’ll offer some additional comments in case helpful or at least interesting…

    When a standard “includes” a lot of things, there is always a risk that it will translate into a laundry list of to-do’s for students. The granular approach to standards exacerbates this risk. (See Grant Wiggins on Granularity)

    In cases where a standard “includes” a lot of things, maybe instead we can think of it as an opportunity to find unity in diversity – to write the kinds of problems and lessons that put ourselves in a position to say to the students, “See? It’s all the same!”

    So, including time in this standard could be a virtue if it helps to give the subject of measurement a unified character. (I’ll note here that time plays a role in my post “Units, a Unifying Idea in Measurement, Fractions, and Base Ten”.)

    A final note in favor of coherence…cluster 5.NBT.A is designated ‘Supporting’ by the two assessment consortia (see here), and that is a reminder that instead of treating this work as yet another disconnected set of tasks, unit conversions might be positioned in such a way as to support of the major work of grade 5. The parenthetical example in 5.MD.1 involves converting 5 cm to 0.05 m; this begins to gesture at how the work of 5.MD.1 relates to other grade 5 work (cf. 5.NBT.A, 5.NBT.7, and 5.NF.B). So in addition to teaching students the enumerated concepts and skills of measurement, the body of work relating to 5.MD.1 could also give students practice with, and insight into, place value, decimal computation, and fraction operations.

    #1993
    TeamMetric
    Participant

    Perhaps, I do not understand the original question. Is Tracy asking if students need to convert from one measurement system (inch-pound) to the other (SI)? My understanding is that the new standards do not suggest the need to convert between only within the same system. Is this correct?

    I briefly looked again, I could not find any text in the standards suggesting the need for students to convert problems from customary (inch-pound) units to SI units. This contradicts some of the sample PARCC prototypes and the approved text book we reviewed in Louisiana- both require a student to convert between systems not just within one.

    This is what I found:
    4.MD.1. Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), …

    5.MD.1. Convert among different-sized standard measurement units within a given measurement system (e.g., convert 5 cm to 0.05 m), and use these conversions in solving multi-step, real world problems.

    Who is responsible for making sure that the standardized tests align with the common core standards?

    #1994
    Jason Zimba
    Participant

    @TeamMetric:

    I could not find any text in the standards suggesting the need for students to convert … from customary … units to SI units

    5.MD.1 is explicitly restricted to conversions within a given system. But 6.RP.3d is not restricted in this way:

    “6.RP.3d. Use ratio reasoning to convert measurement units; ….”

    I would interpret this language to include converting cm to in, or vice-versa.

    (By the way, I don’t think the larger question in boldface belongs on a discussion thread about 5.MD.1. You might consider finding another thread in which to post that question. I will say that both assessment consortia have websites with a great deal of documentation about how they are interpreting specific standards and the Standards as a whole.)

    #1995
    Tracy
    Participant

    The question we were really trying to find is where “time” fits in. For example, we have people who want to convert months to years, decades to centuries, etc.

    #2006
    Bill McCallum
    Keymaster

    Children should grow up knowing that there are 12 months in a year and 10 decades in a century, but it is not obvious to me that it is the math teacher’s responsibility to teach them. Some (most?) kids will learn this at home, some in reading, writing, social studies, or science (it sort of comes up everywhere, doesn’t it?). So, there’s no harm in having a math problem that puts this knowledge to use. “How many months in 5 years?” becomes a question about understanding multiplication once you know that there are 12 months in one year.

    But it seems strange to me to treat this as some sort of conversion rule to be memorized, and I wouldn’t be in favor of having a special unit about it in the curriculum. That way lies curricular bloat.

Viewing 6 posts - 1 through 6 (of 6 total)
  • You must be logged in to reply to this topic.