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Dear Teacher,

Welcome to “Subtraction Mission (Im)Possible”, a module that was designed to help students at LCS, an IBO World School in West Africa, strengthen their skills in the area of subtracting a two-digit number from another two-digit number. The target audience is students who have entered grade 3 without these skills and are in need of additional material to work on independently.

The **terminal objectives** for this module are: ** A. ** Given a total of ten algorithms, including subtraction, addition, and multiplication problems, the learner can correctly identify the four subtraction problems. ** B. ** Given three subtraction algorithms stated in various forms (i.e. in words and in numbers), the learner can recall the process and stack and vertically align the digits in preparation for the subtraction in all cases. ** C. ** Given five subtraction algorithms, three requiring trading, the other two not, the learner can identify the correct path for each of the problems. ** D. ** Given the various steps of the Trade-First Method, the learner can arrange them all in the correct procedural order. ** E. ** Given three subtraction problems (without trading requirement), the learner correctly subtracts first the digit in the 1s place and then the digit in the 10s place in each case. ** F. ** Given ten completed subtraction problems (i.e. four with a correct answer, three with a wrong answer but positive number and three with a wrong answer and negative number), the learner can identify at least five problems resulting in a positive number. Advanced learners will identify the four algorithms with the correct answer.

The overall **instructional approach** selected for this module was constructivism, in particular individual constructivism, thereby including contextualism, to allow students to construct knowledge and meaning through a variety of personal experiences. While the individual lessons show more of an expository approach, inquiry was included were possible. In addition, the lessons were designed and planned with R. Gagné’s (1972) nine events of instruction in mind:
 * 1) // Gaining attention. //
 * 2) // Informing the learner of the objective. //
 * 3) // Stimulating recall of prerequisite learning. //
 * 4) // Presenting stimulus materials. //
 * 5) // Providing learning guidance. //
 * 6) // Eliciting performance. //
 * 7) // Providing feedback. //
 * 8) // Assessing performance. //
 * 9) // Enhancing retention and transfer. //

A variety of media were included in the module (e.g. audio and video files) to support in particular visual and auditory learners.

Please ensure that the students you have selected to use this material have all the required **entry skills**:


 * // Knowledge around digits, numbers and mathematical symbols: // **
 * Recognize the digits from 0 to 9.
 * Name the digits from 0 to 9.
 * Read two-digit numbers from left to right.
 * Count up and down.
 * Recognize the minus symbol.
 * Discriminate between vertical and horizontal.
 * Recognize the different value of digits, i.e. 0 being the smallest and 9 the largest one-digit number.
 * Determine place value, i.e. identifying the 1s and the 10s place.
 * Explain that one 10 is made up of ten 1s.


 * // Knowledge around subtraction: // **
 * Define subtraction.
 * Discriminate subtrahend and minuend.


 * // Computation skills: // **
 * Subtract a one-digit number from another one-digit number.
 * Add a one-digit number to another one-digit number.
 * Add one 10 to any one-digit number.
 * Add a two-digit number to another two-digit number.

Write numbers and draw lines.
 * // Psychomotor skills: // **

If you don’t have current assessment data, please make use of the attached Entry Skills Assessment.





A meeting with the student and a parent is recommended before he/she begins with the instruction to
 * Explain the overall purpose of the module
 * Provide an overview over the material and how to navigate it
 * Discuss how best to complete the module
 * Advice on recommended learning space and time frame
 * Hand out Mission Notebook and link to wiki.

Please download and print the cover page and badge template included in the attached document. Add it to a blank grade 3 math journal to create the Mission Notebook.



While learners are given answer keys to check their work independently in most cases, the completed pre- and post-assessment (see below) will be sent to you, the teacher, for evaluation. Depending on the outcome of the pre-assessment, consider letting students skip the assessments of certain parts of the module. However, encourage them to read/listen/view all materials even if it is considered review for the particular learner. Depending on the outcome of the post-assessment, the student should be guided to make use of the additional resources for either enrichment or remediation.







It is suggested that you complete the module once to become familiar with the material. Please, feel free to contact the designer for questions, clarifications or suggestions to improve this module.

Your feedback would be appreciated for ongoing evaluation of this instruction. Please complete the following questionnaire for each student who has completed the module. Then forward it to the designer.



Thank you. Tanja Galetti (tgaletti@lincoln.edu.gh)