The worksheet titled "Collect the Circles by Drawing Lines in a Grid: A Brain Teaser Activity" features grids that contain circles. Each grid contains a "B" circle and an "E" circle, as well as black circles that are scattered all over the grid. Students start on the "B" circle, and without picking up their pencil, they draw lines going left, right, up, or down to collect all of the black circles. They can't stop on an empty box and change direction, but they can go through the same circle more than once. They must collect as many of the circles as they can. They record the number of circles they couldn't draw a line through in the space provided at the bottom of the page.

Puzzles get progressively more difficult with bigger grids and more dots. Beginning puzzles contain lines that students can use as hints to complete the puzzle, but later puzzles don't, providing students with an even greater challenge.

Brain teasers encourage problem-solving and critical thinking, but they can also be a great way to keep students engaged if they have already finished a worksheet or if there is some time to kill before the next subject begins.

Grid-based puzzles are especially effective because they expose students to grids, which are common in higher-level math problems. For example, the grid can be filled with circles, and students must draw straight lines to collect as many dots as possible.

A puzzle like this is also a good choice because students are encouraged to collect all the dots, but they don't have to collect them all to finish the puzzle and move on to the next one. They can simply write how many they missed. Then, they can compare their puzzle to another student's puzzle and see how they could have drawn their lines differently to collect the dots that they missed, which enhances their problem-solving capabilities.