Review: All the Subtraction Strategies You Have Learned

Look for this idea outside of your lessons. A wise worker does not use the slowest method available. Looking before choosing saves real time. This is worth learning because picking the right subtraction path saves time and prevents errors. Watch for it today, and when you spot it, tell someone what you noticed and how you knew. Ask yourself where else the same idea might be hiding, then go and look.

Let us look at this together. Subtraction has its own toolbox. You can cross out pictures. You can count back for small take aways. You can count up when the numbers are close.

You can use a known addition fact. You can find the missing part on a part part whole mat. Try 15 minus 12 and notice that counting up takes only three steps while counting back would take twelve. Choosing well is the whole skill.

Watch out for using one strategy for everything. Counting back is fine for minus two but painful for minus nine. Look at the second number first: small means count back, close to the first number means count up. Say it out loud once, and then try it with real objects.