This math journal focuses on two-digit addition problems solved using a variety of strategies (open number line, expanded form, standard algorithm), but each problem is solved incorrectly. Students will strengthen their conceptual understanding of 2-digit addition through error analysis and critical thinking. There are 20 different problems, including some word problems, for students to practice finding and explaining errors, as well as explaining WHY the error is incorrect and how to correctly solve the problem.
You can print these out for each student to use as a warm up activity, or as a math journal, or in a math center. You can also project the PDF and have students partner talk and share their analysis and solutions with the class.
I've created one problem and solution per page, in order to leave students enough room to write out their analysis and solutions, but you can always change your printer settings to print two to a page if you want to cut down on the amount of paper. Or you could paperless and use this resource with SeeSaw.