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Conservation of Number Checkup

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What are you trying to do?

  • Spot check your Low Block Foundation/Year 1 (Early Stage 1 or Stage 1) students for their ability to conserve number, In readiness for a focus on simple adding and subtracting. These students should already be able  to 1-1 match oral number words to objects accurately.
  • To conserve number means that a young student understands a quantity does not change if it is rearranged, covered up or hidden behind a box. A student who can conserve number is ready for the concept of addition where you can count on to find the total of 2 groups. A student who can conserve number can also count back to find the difference between 2 quantities.
  • A young student who cannot conserve number doesn’t understand that a quantity remains the same when it is rearranged. This student is able to 1-1 match number words to objects but continues to recount when objects are rearranged. These students solve addition problems by counting all objects one by one. This is a Count All strategy, which is NOT an addition strategy.  You can’t expect these students to participate effectively in any addition or subtraction classroom experiences. You need to identify these students before you focus on any addition or subtraction experiences.

Suggested Checkup Process

You need:

  • 12 colourful counters e.g. frogs, cars, fish …
  • A few minutes for each student interview
  • F/Year 1 (ES1/Stage 1) Conservation Checklist (available to subscribers in the Counting activity files)

What do you do?

  • Ask the student to count out 8 objects for you and to place them on the table.
  • Next tell the student that you are going to put these “frogs” together in pairs e.g. rearrange the 8 objects into 2 lines of 4.
  • After the objects are rearranged, ask the student; “How many frogs are there now?”  Notice the student’s response. Some students will automatically say “8” so you can confidently mark their name off as a conserver on your checklist.
  • Some students will look at you as if to say “…but I already told you that…” but they will still recount. You need to rearrange the objects a third time, e.g. in a curve. Again ask: “How many objects are there now?” If they are a conserver they will definitely tell you “8”. You can then mark them off on your checklist.
  • But if a student recounts all the objects this third time, it is a strong indication that they cannot conserve number. These students are not indicating their readiness to experience adding 2 sets together. They need to experience counting objects, covering them up and then saying how many there are altogether. They need to “trust” objects. It may take some time focusing on similar activities to this before they realize that the number of objects does not change if they are rearranged or hidden. These students are definitely not ready to investigate adding and subtracting objects from a given group.