Room 3 has been learning about Matariki and integrating our learning into maths. Based on the Matariki legend of Tamarereti, we all took part in a place value subtraction task.
The story of Tamareretei can be found on Youtube.
The first challenge was to get a set of 200 items to be our stones from the fire. We had to organise the “stones” so someone could easily check that there were 200. When it had been checked that we had 200 stones we had to put them into our waka.
Tamarereti’s journey took him from the northern part of Lake Taupo to the southern part. On a map of Lake Taupo we had to record Tamarereti’s journey. We pretended Tamareretei was in our waka, throwing handfuls of stones out as we travelled across Lake Taupo to light our way so the Tanawahi would not eat us.
The maths part of this activity involved subtracting each handful of stones thrown out of the waka as we travel across the lake. We had to throw at least 10 handfuls of stones as we crossed the lake. We also had to make sure we still had some stones left in our waka when we reached the southern shore.
We recorded the number of stones we threw out of the waka and then the total of stones left in the waka on a blank number line. Then we had to plot our journey and the number of stones we threw out each time on a map of Lake taupo. The really tricky part was at the end when we had to work out if our subtraction was accurate and check if we had the same number of stones left in our waka as our subtraction predicted.
Our group got our 200 rocks really quickly because we counted in tens.
We counted 20 bags of ten. We knew that 20 groups of ten is the same as 200.
Our group took a really long time to get our set of 200 rocks. We were using the bottle caps. We all started doing different things and then we didn’t group them in tens so we lost track of our count. We needed to be more organised.
I made ten rows of ten with the bottle caps for one hundred and then we put another layer on the top to make 200.
There were only 150 jenga blocks for our stones so we had to make it up to 200 by using dominos.
We really wanted to finish subtracting our stones, it took a long time.
After our journey across the lake we found we had eight extra stones left in our waka so we must've not been accurate with some of our subtraction.
This maths was hard and frustrating and it took us a long time and we didn’t have the right number of stones left.
Arley and I were the first ones to get our waka across the lake. We did our subtraction by taking away the tens and then the ones but we still had some stones left.
Subtraction Strategy Discussion
We are learning to find efficient strategies for subtraction. We agreed our most successful subtraction strategy was to take away the tens and then the ones. Some of us found we went back to counting backwards to subtract when things got hard. This was often when we lost track of where we were at. When we were subtracting numbers less than 10 some of us used a back through 10 strategy for example 134 - 8, we solved as 134 - 4 = 130 - 4 = 126.
This was a challenging task for us. 200 stones was a lot to keep track of. Some of our groups were too big and this made it harder for us to work together. Another subtraction task starting with a smaller number for example 100 or 50 would be a good next step. Using a bead string or an abacus to keep track of our changing total would also help us. Highlighting the relationship between addition and subtraction and using addition to check our subtraction is another next step.
Mathematics Achievement Objectives: Number and Algebra level 2
nzmath.co.nz - Matariki Maths Level 2
Matariki, legend, Tamarereti, subtraction, place value, Lake Taupo, Tuwharetoa