I love using proofs as quick assessments be it formative, summative or a quick check-in. These students worked together to prove the statement is false using several methods – a range of manipulative is always on hand and the students are able to use them in flexible and often ways not intended by the manufacturer.
Here the students demonstrated an understanding of:
- equivalent fraction
- decimal conversions
- place value
- recurring decimals
If you are to use a prompt as a summative assessment then I would recommend either asking the students to present their work or conducting short conferences.