I wanted to share a favorite math warmup activity in my room! My first graders love these "number mysteries". They can't get enough of them. The concept is simple. I give the students "clues" about the math mystery and they need to fill in the grid to "solve the mystery".
The numbers in each row/column need to add up to the clues on the notebooks at the end of that row/column. Generally I only give them the clues on the outside of the grid, but occasionally I give them a few numbers on the inside as well (as either an added challenge, or as an extra support - it could go either way). After a student has solved a number mystery, they partner up with a friend to check each other. Obviously there was a little bit of fact checking to be done on this one :)
We often share out different solutions whole group as well. After the students get comfortable with one level of mat, we move on to more complex grids, or larger numbers. The possibilities are endless.
After a while of doing these, the students always want to make up their own mysteries to give to their friends. I teach them to fill in the grid first, add up the rows and columns to get the clues on the outside of the grid, and then erase the numbers inside the grid and have a friend solve. They get such a kick out of making the mysteries themselves!!
In the number mysteries pack I have given you 3 levels of mats student and teacher mats, and for each level I started you off with 18 sample mysteries (but you can easily make your own up-- just be sure not to make an addition error and accidentally give your entire class an unsolvable mystery!! Been there, done that!)
You can grab this pack in my store by clicking on the picture below.