I started using it when I was 8 and grew the worst hatred I ever had for it. The entire website is frustrating, which led me to start crying at least 50 times. My parents still make me do it anyways. I've started getting the worst anger issues possible due to this website. I've literally even tried breaking my laptop with my fists. If your a parent, trust me on this. Your kid will gain depression from this website. Don't make your kids use it. Consider this as a warning. The questions are super confusing and It still didn't help me understand equivalent fractions. Don't let ur parents find this website kids. Your life WILL be ruined.
Answer: There is an old adage in education, that 'Spaced' learning is more effective than 'Clumped' learning. Waiting for the next Mastery challenge teaches patience, allows you to practice more skills in the dashboard, so the mastery challenges have more to do assessment on, and as you note, ensure that the concepts are transferring from short-term, to long term memory in your brain.
Khan Academy has a rating of 2.3 stars from 89 reviews, indicating that most customers are generally dissatisfied with their purchases. Khan Academy ranks 91st among Math sites.