Lesson Study Video for Thinking Systematically: Class Discussion (4 of 6)

Class Discussion (4 of 6)

This main part of the lesson concludes with the teacher checking students’ notebooks for progress on their tables, and by asking if all possible entries have been posted on the board. Several more cards need to be prepared and these are placed on the board. Some students have noticed from their own tables that the total cost falls by 30 yen as one goes from one ordered pair to the next – that is, as one less ball-point pen is replaced by a further pencil.
The teacher then asks students to take the completed cards from the right hand side of the board and to place them in order using the template established at the start of the lesson. Having students complete the table, the teacher adds a further hand-written entry for (0, 10). The teacher asks students to comment on what patterns they can see from the completed table. Patterns between the ordered pairs are specifically mentioned as well as the 30 yen difference in total price between each entry.

The teacher then asks students to identify the solution to the original problem. This is given as (2, 8) – that is, two ball-point pens and eight pencils. The teacher asks if there are any other possible solutions. Someone proposes a solution involving decimal values. This kind of solution is not considered realistic. It is possible that the lesson might have ended here.

Back to Thinking Systematically