Which unit of time measurement came first?

Lead In:

With a partner, we wrote on bits of paper as many different units of measurement for time we could think of.  Eg, hours, years, centuries etc
(Walking around and seeing their ideas gave a good assessment of where certain children are at with their understandings)

Activity:

We then arranged them in ascending order and then shared with another pair what they had thought of and how they had arranged their units.

Interestingly a few partners had included an eon as a unit of measurement for time as well as infinity so we had a good discussion about what they actually meant.

Creating Theories:

We then thought about which of those units of measurement for time we felt would have been created first.  We reflected slightly about how we have learnt about the role astronomy plays in our measuring of time and they were reminded to think about their previous enquiries into sundials, water clocks and Egyptian merkhets etc.
With their partners they discussed and tried to arrange all their units of measurements in an order they felt were created first and so on.  Some really great discussions and different points of view were emerging from this.

Sharing:

They then shared their theories with another pair and tried to combine both their theories into a new theory.  We later did a 'gallery walk' to see what the other groups had theorised and had time to discuss why they placed certain measurements where they did.

Reflecting:

We then gathered as a whole class and found out what we thought were at least the first three units created as well as the last.

Through our discussion, we eventually agreed that:

1. Days were created first as a unit of measurement for time
2. Hours came next
3. Seasons came third

We figured that the Ancient Egyptians, being were the first civilisation to start measuring time would have needed to measure seasons for growing their crops. Makes sense to me......

On the other end, we couldn't come up with an agreed upon measurement that was the most recently created- it was a toss up between eons, the concept of infinity and millenniums.  All three were supported with reasonable theories and supporting evidence so we left them grouped together on top of each other.