SAMR is currently a huge buzz word! And I don’t claim to be an expert on this model, so I may be incorrect with the rest of this post (comment to help me set the record straight). I believe that today’s app(s) would help Modify a typical aspect of elementary math, equivalent measuring.
Curious Ruler ($0.99) or Ruler | A Curious Tool (free) allows you to select a reference object from their selected list to use to measure another random object with the iPad’s camera. After you take a picture of the two items together, you mark off the sizing so the app can get you a measurement as well as an equivalent measurement. Below are some screen shots of my measuring.