A quick self marking starter - differentiated into two sheets - One sheet on 3 digit integer subtraction and one on decimal subtraction. The answers to both spell out the punchline to a joke which is what you use to self mark - if the pupils get the correct punchline then they’ve completed the worksheet correctly. Both sheets feed into the same joke so although your class are split into two groups working on either decimal or integer subtraction - everyone is working on the answer to the joke “Why did the computer get glasses?”. Great little activity, will take about ten minutes but a good way of quickly assessing your classes subtraction skills before you move into the main activity. Good motivator for a challenging class too to get everyone settled at the start of the lesson.