How Many in the Bag?
Before the Activity: Each pair of children should have one bag. Place from 11-20 counters in each bag. On the outside of each bag, write the number of counters contained inside.
Part 1: Begin by showing the children a bag containing exactly10 counters and by placing a Ten Frames transparency on the overheard. Have a student reach into the bag and remove some of the counters and lay them in the Tens Frame. Talk about how many were removed and how many remain inside. Have the students discuss their answers. Point out that when the counters have been removed and placed on the tens frame, it is often not necessary to count the remaining ones. They can check their answer by removing the remaining counters from the bag and counting them. Repeat this activity several times.
Part 2: With another bag put 14 counters in it. Remove a handful of counters and place them on the overhead. Ask how many are left in the bag? Students should explain their answers. If no one suggests the counting up strategy, model it. (Page 32) Repeat this proves several times.
Before the Activity: Each pair of children should have one bag. Place from 11-20 counters in each bag. On the outside of each bag, write the number of counters contained inside.
Part 1: Begin by showing the children a bag containing exactly10 counters and by placing a Ten Frames transparency on the overheard. Have a student reach into the bag and remove some of the counters and lay them in the Tens Frame. Talk about how many were removed and how many remain inside. Have the students discuss their answers. Point out that when the counters have been removed and placed on the tens frame, it is often not necessary to count the remaining ones. They can check their answer by removing the remaining counters from the bag and counting them. Repeat this activity several times.
Part 2: With another bag put 14 counters in it. Remove a handful of counters and place them on the overhead. Ask how many are left in the bag? Students should explain their answers. If no one suggests the counting up strategy, model it. (Page 32) Repeat this proves several times.