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?
Nathaniel : 3242  Carlos : 2323 
Alex : 2333  Bryan : 4222 
Jagdish : 4114  Julian : 1134 
Sean : 2311  Carter : 3232 
Hayden : 4311  Jeremiah : 4443 
Cole : 3431  Brayden : 1242 
Wyatt : 3243  Chase : 4414 
Steven : 4224  Timothy : 2312 
Dominic : 2122  Sebastian : 4131 
Xavier : 4424  Jaden : 4242 
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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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 such as tablets, iPads or Laptops? This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments: Transum.org/go/?Start=May27 However it would be better to assign one of the student interactive activities below. 

Here is the URL which will take them to a related student activity.