This 9 minute video (with commentary) explains how earlier work on addition and subtraction can be extended to larger numbers. The video focuses on calculation methods based on doubling and on bridging, before exploring the ‘Basic 8’ strategies.
Two related games are shown in this video, both designed to practise the ‘Bridging through 10’ technique. One game is called Frame an Addition and the other is Frame a Subtraction. (A 3 minute silent stop-motion movie.)