Estimation 180 is a site run by educator Andrew Stadel who presents his students with an estimation challenge every day of the school year. This practice helps kids develop their number sense and problem-solving skills. On the website, he shares his challenges with educators across the world. These work well for warm-ups in the classroom, but could also be effective for daily challenges in the e-learning setting. Since so many educators and students are stuck at home during the pandemic, Stadel has also created an estimation scavenger hunt challenge for these difficult times. Try this with your learners today!