Students will learn how to plot integer coordinates. Next, give your students this challenge. Finally, lead this investigation. Continue reading only after you've watched the video. Correct guesses are worth one point and incorrect guesses negative one point. A poke is neutral. Students win a level if they reach a certain number of points. I think the number of points should be some fraction of the number of squares in the level, and students should be able to guess larger fractions as they proceed from level to level. For reference, there are 17 squares in a 7x7, 22 in a 9x9, 19 in a 10x10, 33 in a 12x12, 31 in a 13x13, and 39 in a 14x14, and 31 in a 15x15. So maybe on the first level the score should be 1/3 of the total number of squares, rounded down if necessary. So if the first level is 7x7, we have 17 squares, and 1/3 of that rounded down is 5. A better scoring system would take into the actual guesses made by students. If you try this activity in your classroom, please record student scores for each level and send them to me. This data would be useful to other teachers conducting this investigation.