# Teachley: Subtractimals

Teachley: Subtractimals by Teachley is the latest app by the former teachers and experts in children’s cognition and learning from Teacher’s College, this app is the follow up to Addimal Adventure the Winner of the Apple Design Award 2014. This exciting new app uses cognitive science research to assist in teaching effective subtraction learning strategies to solve number facts. Unlike most current math fact apps that function as drill-based games or digital worksheet applications; Subtractimals provides the user a choice of strategies such as counting back, counting on and memory. The teaching of specific strategies in this instructional tool is one of the number one features that we believe students will enjoy and feel comfortable in exploring subtraction.

Subtractimals uses blocks (or as teachers of elementary students call them manipulatives known as Unifix cubes with flats, rods and units) as the primary visual representation to assist students with their subtraction strategies in both of the Tool Rounds of Counting On or Counting Back. The user must first select one of the tools to start. A cute green frog represents the counting back strategy by slurping up blocks. Students can tap the Frog while counting back one by one to get to the answer. Number hints help students know which number to say as they count back. For example, solving 5-3, the number hint shows 5, 4, 3, ?. More advanced students can touch/hold the frog to slurp up multiple blocks at a time. The subsequent part-part-whole representation helps students visualize the problem.

The tool of Counting On also utilizes what the creators of Teachley refer to as blocks, but these blocks differ from the typical Unifix cubes in that the traditional manipulatives teachers tend to use in the classroom are single unit blocks as stated above. Whereas Teachley’s blocks are continuous and do not initially show individual unit blocks. This concept based on their research is great to assist in promoting the concept of cardinality and fosters more advanced strategies, but for children who may be struggling to master basic subtraction facts these blocks can be quite perplexing and challenging. The tool of Counting On is represented with a cute blue frog that makes this annoying “dwee” sound as he counts on. Children might find the sound that the blue counting on frog makes cute, but we believe it would be much better if he could actually count on using numbers or at least say “one” every time he added a unit.

The basic premise behind this app is engaging and fun to use. The Tool Round features interactive tools that model the effective strategies of Counting On or Counting Back to assist children in solving subtraction problems. There is a Memory Tool but you have to be quick because it only stays active for 3 seconds. The developers clarified that the memory tool becomes inactivated after 3 seconds as an intentional feature since if the student does, in fact, has the problem memorized, the child should be able to answer in this time frame. If the child doesn't have it memorized, they should not be using this strategy.

I found the Speed Round as most of the students I explored it with, to be the most fun and engaging because you really wanted to try to solve the subtraction problems as fast as possible in order to earn the gold box stars. The user visits what appears to be outer space. A giant spaceship character cuts the first chain of the subtraction fact that is being held over a pot of molten gold after a quick second or two delays. If the user answers immediately before the second chain is cut they receive a golden star block as opposed to a green one for a slower response or worse yet a red one for an incorrect response. These blocks are then used to fill in a hidden pictograph to reveal an illustration. This Speed Round was truly the most fun and actively keeps the user engaged in wanting to solve more facts as quickly as possible to reveal the hidden picture. It also makes you want to get through the tool rounds quickly but the method of clicking on each frog to wait for him to slurp up or “dwee” back at times was slow and not as instantly gratifying for me and I know it was for the students! For this reason, you can touch and hold the frogs to slurp or spit more than one block at a time.