In today's lesson, we are focussing on ways that we can 'subtract' lengths from one another. It would be helpful to begin the session by thinking about the ways that we can subtract. What would I get if I subtracted 45 from 87? What about 64 subtract 32? Which strategy did you use to figure these out? Remember that in today's session you will be free to use whatever strategy works best for you. Use the video above to introduce the key concepts of the session, then select the challenge that suits your level of learning.