On the face of it, the numbers look good.

Completing The Names We Carry post reminded me of an activity I use with pre-service teachers involving Cuisenaire rods and what we call a “Hundred Face” (Find a lesson plan from AMSI here).

Initially, I had intended to include this at the end of The Names We Carry, but I felt it was becoming a story in its own right. What started as a connection between names and faces was taking me back into mathematics, and particularly to one of those activities that looks deceptively simple but has far more going on underneath.

For those unfamiliar with Cuisenaire rods, they are coloured mathematical rods with values ranging from 1 (a white cube) through to 10 (an orange stick equivalent in length to 10 white cubes). The challenge is to create a face using rods that total 100.

Initially, we make fairly basic faces, but then I add a rider: they must include at least one rod of every colour. Suddenly the task becomes much more interesting. They now need to think much more carefully about combinations, values, structure, and checking totals. The faces become more complex, more creative, and far more individual.

What fascinates me is how quickly personality emerges from arrangements of simple mathematical objects. The rods themselves are just coloured wooden blocks, yet somehow students create faces with expressions, moods, and character. Some faces look cheerful, some mischievous, some startled, some thoughtful. It is amazing how quickly we begin to see identity in patterns and relationships.

Why do I use this activity with PSTs? Because they are future primary teachers, and this activity can easily be adapted for a Year 1 classroom as part of a unit on place value and numbers to 120.

At the beginning of the unit, students can create a Hundred Face as a form of pre-assessment. The way they construct the face tells you a great deal about their mathematical thinking. Some children use very simple constructions and rely heavily on smaller rods or repeated combinations. Others demonstrate more sophisticated understanding of grouping, equivalence, and efficient combinations.

Then, at the end of the unit, students complete the task again, this time with the additional condition that they must use at least one rod of every colour. Suddenly they are required to think much more deeply about how numbers can be composed and recomposed to make 100, while also needing to justify and check their thinking.

What I love most, though, is that the activity becomes about far more than simply reaching 100.

There is no correct Hundred Face. There is a condition — the rods must total 100 — but within that condition there are countless possibilities. Two students can use exactly the same mathematics and create completely different faces. Or they can create faces that look remarkably similar using quite different combinations of rods.

That matters.

Too often, particularly in primary mathematics, we give children the impression that mathematics is about producing the answer, preferably using the method the teacher has just demonstrated. Hundred Faces turns that around. There is a fixed destination — 100 — but an enormous number of ways of getting there.

Adding the requirement that every colour must be used makes it more interesting again. Now students cannot simply find one convenient combination and repeat it. They have to decompose and recompose 100, consider equivalence, keep track of what they have used, and decide whether replacing one rod with several others preserves the total.

And all the while, they think they are making a face.

Perhaps that is one of the things I like most about good mathematical tasks. The mathematics doesn’t have to announce itself loudly. Students can be creating, arguing, rearranging, checking, noticing and changing their minds while quite sophisticated mathematical thinking is happening underneath.

But something else happens with Hundred Faces.

Somewhere amongst all that decomposing, recomposing and checking, coloured rods begin turning into personalities.

One face looks cheerful. Another looks thoroughly unimpressed. One appears startled by whatever has just happened outside the photograph. Another looks as though it would like to speak to the manager.

They are Cuisenaire rods. They don’t have personalities.

And yet we give them personalities almost immediately.

We look for the person.

Perhaps that is not entirely unlike learning people’s names.

At first there are faces. A room full of students. Names on a class list. People I see for a few hours each week.

But gradually the individual emerges.

The quiet one with the wicked sense of humour. The one who challenges everything. The one who lacks confidence but keeps going. The one who suddenly sees something mathematically and lights up.

Eventually the face isn’t just a face anymore.

There is a person attached to it.

And then, if I’m lucky, I might even remember their name.