Here's a fun activity to review how oxygen travels from outside the body to the lungs and back to the heart. Students must navigate through a digital maze and answer 18 questions. One question is shown on the maze as the students begin the activity. A path appears, and the next question pops up as the students answer correctly. Incorrect answers reveal nothing, and students must reattempt the question to move along successfully in the maze. Students will continue on the path until the end. This NO PREP, self-checking digital maze is great for homework, assessment, and science centers. An answer key is included.