Guided Lessons

### Lesson plan

What’s the missing link? In this lesson students will explore missing factors using three digit numbers. Using their knowledge of skip counting, students will determine the missing links.

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Students will be able to find missing factors when completing three digit addition problems.

(5 minutes)
• Invite students to sit in a circle.
• Tell the students that they will be tossing a bean bag to the person next to them as they skip count.
• Give the students a starting number such as 24 and a skip counting pattern, such as for them to add three.
• Invite students to add on three to the previous number before tossing the bean bag to the person next to them.
• Tell the students that they will be learning how to use addition to find Missing factorsIn three digit numbers.
(5 minutes)
• Tell the students that a Missing factorIs an unknown number. It can be in a sequence of numbers or in an addition problem.
• Tell the students that they are going to make connections to skip counting and find missing factors in the middle of number sequences.
• Using a number pattern of choice with a blank in the middle (such as 326, 328, ____, 332, 334) show the students how you can analyze two numbers that are next to each other and determine the pattern. For example, 326 + 2 = 328And 332 + 2 = 334, so 328 + 2 = 330. The missing factor is 330.
• Show the students how to use this pattern to find the missing link in the number sequence.
(10 minutes)
• Divide the students into small groups of three or four students each.
• Distribute one set of numbered index cards to each small group.
• Write the following sequence on the board and ask each group of students to place the cards in the following order: 225, 229, ____, 237, and 241.
• Ask the students to work together and figure out how much is added to each number to get the next number.
• Challenge the students to find the number that is the missing link.
• If needed, give the students additional number sequences to practise in a small group.
(15 minutes)
• Ask the students to complete the Number Pattern Parachute worksheet.

Enrichment:

• Invite students to use the Tidy Sum 1000 worksheet to play the game together.

Support:

• For students who have difficulty with the abstract concept of finding missing factors, invite students to create base ten drawings or to draw as they count on.
• Allow students to use base ten blocks to represent the abstract numbers.
• Invite students to create digital representations of finding the missing links (factors) such as creating a diagram or an electronic drawing that shows how factors in sequences are found.
(5 minutes)
• Distribute individual whiteboards and whiteboard markers to the students.
• Ask the students to complete the following sequence, finding the missing addition links on their whiteboards: 653, 658, 663, ___, 673, and 678.
(5 minutes)
• Ask students to share how the strategy of finding missing links or factors is different from other addition strategies.
• Invite students to think, pair, share with their neighbors and then to share in a class discussion.