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The concept of 10 more/less is a beast in the primary grades.  Last week I realized that I’ve been feeding the monster that I’m continually trying to defeat. Almost every day, in every K-2 classroom across the United States students encounter this guy:

I made a conscious effort to pop my head in every K-2 classroom in the schools I visited this week.  It was great to see that every classroom had a traditional 0-99 or hundreds chart posted like one above.

While visiting, one of the teachers asked if I could come back today and model a lesson using a 0-99 chart because her students “just weren’t getting it.”  I gladly accepted her invitation and showed up with this guy:

I didn’t use manipulatives for this lesson because I was specifically focusing on the rote counting process which precedes one-to-one cardinality when counting by ones OR tens.

This 30 minute lesson is about as unscientific as it gets when it comes to research but here’s my take-aways:

• The traditional hundreds chart is counter-intuitive to how students understand and recognize number.  When numbers increase by 10 or more, they go down.
• The hundreds chart is set up to mirror reading (left-to-right, top-to-bottom).  But just because we do it in reading, does it mean that we have to apply that same idea to math?
• By inverting the chart and starting with zero at the bottom, students were able to explain that when the number increase by ten it gets larger/taller/bigger/greater which are all modeled when they move “up”.
• A student made the best connection EVER when she said “It’s like my carton of chocolate milk. When I drink some there’s less and it goes down. But when I spit it back in there’s more milk and it goes up.
• I took that student’s reasoning and applied it to the traditional hundreds chart (which I didn’t share).  When we put more in, it goes down.  When we take milk out, it goes up.  When in life does this ever happen?

It comes back to the ol’ “which way does a ten frame go?  I think students should see the ten-frame both ways.  I just don’t think I’m giving the hundreds chart the same opportunity.  If anyone has some or knows of official research on this please share.

If you flip the chart please let me know how it unscientifically goes!

Bottoms up and stay thirsty my friends!

Update October 2016: Jenny Bay-Williams recently shared this article from 1974 regarding a flipped hundreds chart. Not surprising to see that we haven’t changed a thing.