On the Mathling Bullet Train the rails over a bridge have broken apart due to rust. Because of the broken rails the trains will stop moving and if they're not fixed properly the trains could fall into the chasm below. We have prepared replacement rail parts for the already broken ones, and need help slot the new parts in. Slot them in by dragging the number rails into the missing slots. Make sure that the numbers all add up to the rail which is in good condition on the far left. Students will learn how to use number bonds by adding up 2 parts to make a whole number.