PS/IS 686 | Brooklyn, NY

5th Grade Math: Olympiad and Place Value

Just a reminder: the second Olympiad contest will take place tomorrow.

Fifth graders began exploring place value this week.  We looked at strips that measured 1cm, 10cm, and 100 cm long, and called them A, B, and C respectively.  Last year, we built these and predicted how far around the room 1000cm would stretch.  This year, we didn’t do any building, but we thought about how we could create plans for building strips D through G, using strips we already had.  

This investigation really encouraged us to look at how place value works.  We noticed that each strip was ten times greater than the one before it, which is how our place value chart is organized.  We also noticed that if we use a strip that is ten times as long, we will need ten times fewer of them. This also relates to our understandings for factor/multiple relationships.

Today, we moved away from the context and thought about how we could rewrite these large numbers in a different way.  This is where exponents come in.  We looked at how we could write powers of ten using exponents.  Students noticed that if 10 is the base, the exponent tells us how many zeroes will be in our total.  We also discussed why this is true, and it related to our previous understandings of multiplying by ten.

Later in the week and next week, we will think about these numbers 3-dimensionally as opposed to linearly with an exploration into the “shape” of numbers. Stay tuned!