The teacher thinks of a four digit number made up of digits in the range 1 to 4. Each student guesses what the four digit number might be. The teacher gives one tick for each digit the student has in the right place. What number is the teacher thinking of?
Jack : 2221  Caleb : 3441 
Justin : 1313  Austin : 1441 
Evan : 4234  Thomas : 1122 
Luke : 1341  Mason : 3242 
Aidan : 3231  Jackson : 4341 
Isaiah : 3222  Jordan : 2213 
Gavin : 3122  Conner : 3434 
Aiden : 1213  Isaac : 3123 
Jason : 3143  Cameron : 2333 
Hunter : 4411  Jayden : 3322 
Note for Teacher: All of the students guesses above will probably not fit on the screen at the same time. You may wish to keep the lower guesses hidden so as not to make the activity too easy.
Topics: Starter  Logic  Puzzles
Y5/6 working hard on the @Transum starter of the day. Fabulous maths reasoning and thinking skills. We love maths! pic.twitter.com/erhZztb4Nc
— Red Hill Field PS (@redhillfield) May 27, 2016
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Change Numbers: 

Note to teacher: Doing this activity once with a class helps students develop strategies. It is only when they do this activity a second time that they will have the opportunity to practise those strategies. That is when the learning is consolidated. Click a button above to regenerate another version of this starter from random numbers. There is a choice of three levels; easy, medium and hard.
Advanced: Finding a unique solution may not be possible. 

Possible strategy: Make a grid showing the possible digits which could appear in each of the four positions. By looking at the clues which do not have any ticks by them, cross of the digits which can't appear in each position.
There should now be only a limited choice for the correct digits:
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Teacher, do your students have
access to computers? 

Here a concise URL for a version of this page without the comments.
Here is the URL which will take them to a student version of this activity.
Transum.org/go/?to=frustration