Cash check: Directives for lower secondary level

Material: A small, a medium-sized and a large coin
Duration: 20 to 30 minutes

1. The students are sitting on their chairs without being able to see the teacher (for example with their backs to the teacher), possibly with their eyes closed.
2. The teacher drops three different coins successively onto the table.
3. Each student notes down individually which coins he/she heard. The result is not revealed, neither among the students nor to the teacher.
4. The teacher then drops the same coins in the following order: large / medium-sized / small / large / small coin.

The coins are always dropped successively onto the table.
5. Based on his/ her assumption, each students notes down his/her calculation with the corresponding result. The different results are listed on the blackboard.
6. The students work in pairs to find out the corresponding calculation for each result and name the coins used.
o Are there results that are impossible or unlikely?
o Are the different solutions leading to the same results?
o Are there additional possible results? (List on the blackboard)

7. Which is the correct result? Argue, wager, compare,...

to the Observation form

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