My planning/reflection for this question:
Q1: Bo's Lollies
Bo has 120 lollies. he gave half to his sister. Then he ate [6,16,26] How many did he have left?
Bonus: Bo has 120 lollies. He gave some to his sister. Then he ate [6,16,26]. At the end he had 54 left. How many did he give to his sister?
Bonus: Bo has 120 lollies. He gave some to his sister. Then he ate [6,16,26]. At the end he had 54 left. How many did he give to his sister?
Logan's Lego
Logan had [144,140] bits of Lego. He was naughty so his mother took away 1/2. Then Logan lost [8,18,48] more. How many did he have left.
Bonus: Bo has 186 lollies. He gave some to his sister. Then he ate 17. At the end he had 32 left. How many did he give to his sister?
Bonus: Bo has 186 lollies. He gave some to his sister. Then he ate 17. At the end he had 32 left. How many did he give to his sister?
Big Ideas:Read and understand a subtraction question
Show subtraction thinking on a number line Basic facts to solve other problems eg. 10-6 can help with 60-6 eg. 14-7 can help with 140-70 Splitting a number make subtraction easier eg -18 as -10 then -8 |
Small Ideas:
1/2 (the symbol) is the same as half (the word)
Halving is splitting into two groups Counting in 10's |
Expected Responses |
Plan |
Draw all the lollies - try go back in ones
Do only the first part of q Get stuck on material choice (because over 100) Tens on first, count back in ones on second Struggle to split 120/140 even with materials Partition 120 with 50, 50, 10, 10 Incorrect recording on NL - eg not writing numbers in correct places. Not showing what is being taken away. Rounding and Compensating. Tens on first, count back in ones on second Down through 10 |
Direct to better materials
Act out problem Allow to struggle then direct How could basic facts help? Help act out with materials Teach how to show thinking on paper Model, link to story, understand each number Include in sequence? Prolly not...not linked closely enough to big idea. Included in sequence Included in sequence |
The SC
At this stage i was very comfortable that my question would allow the kids to really explore the big ideas that I had in mind. I had thought about what I could potentially sequence as a result of their work.
Scaffold for Student Conversation
Student Response and Sequence
While this was not really part of the big ideas I still chose to sequence it because splitting the 120,140 was a big part of the problem.
After the discussion of how the first number was spit this was the first idea that I sequenced. It was a fantastic example of stage 4 four thinking. Everything was counted back in tens and ones. They exchanged tens frames for counters when they needed to split up numbers. One particular reason I chose this was that they had clearly set out and preserved each part of the question. We annotated the picture as part of the discussion.
I chose the work below to sequence becuase it was also stage 4 BUT they had shown their thinking on a number line which was one of the big ideas that I wanted to push. All of the working out was done in a similar way to the group above but they chose to represent it in a more sophisticated way.
Below extended the sequence because they did not count back to solve the 70-8 they used basic facts (the three equations at the bottom was my recording of their thinking as they explained it to me).
This final image is the final example of student work in the sequence. I chose this because it contained an example of partitioning the 18 into 10 and 8 to make subtraction easier.