subtraction 4 digits

Once upon a time, there was a farmer who had 20 sheep. One day, 8 sheep got lost. We can write this as a subtraction story: 20 - 8. To find out how many sheep are left, we start with 20 and take away 8. We can break 20 into 10 and 10, and 8 into 5 and 3. First, take away 5 from one of the 10s, we get 5 left in that part. Then take away 3 from the other 10, we get 7 left in that part. So in total, there are 12 sheep left.

There were a few points worth reflecting on in the teaching of deduction: 1. ** Arithmetic understanding **: When the students are asked to work together in small groups to self-study the calculation of deduction based on their existing addition calculation methods, although the students can come up with a variety of methods and participate actively, if the teacher does not emphasize the relationship between minuend, reduction, and difference enough, it will cause students to make mistakes such as using reduction to reduce difference or difference to reduce reduction. This shows that a thorough understanding of the calculation theory is crucial. 2. ** Teaching arrangement **: For example, the addition and deduction calculation is divided into two classes because students made more mistakes when doing addition and deduction homework. In the teaching of addition calculation, by adding review questions to pave the way for new knowledge, students could be motivated. Students could also quickly discover the calculation method, and they could also use the student's name to increase their participation. However, if only the addition calculation was taught, the amount of practice in the classroom might not be enough, and the slow calculation speed of the students would affect the practice density. 3. ** Overall teaching planning **: You need to understand both the teaching materials and the students. The life situations in the teaching materials (such as the scene of buying things containing addition and substitution problems) could be used to introduce new lessons and lead to verification teaching. At the same time, they had to make clear the teaching objectives (such as letting students learn the calculation method of addition and deduction, developing the habit of checking, improving the accuracy of calculation, etc.), the key points (addition and deduction checking), the difficult points (the variety of checking methods), prepare the teaching aids, and also consider how to take care of the poor students, design the teaching links (knowledge laying, questions, homework, knowledge extension, etc.). 4. ** Teaching Method **: The teacher should not talk too much. The classroom should be returned to the students so that the students can learn the knowledge of deduction calculation through self-study and exploration. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The following is a possible reflection on the teaching of continuous substitution: ** I. Teaching of calculation methods and students 'mastery of them ** 1. ** Calculation accuracy and speed ** - When teaching continuous substitution, it was similar to abdicating within 20. Some students might have problems with slow calculation speed or insufficient accuracy. For example, for a three-digit substitution with continuous abdication, like 435 - 276, students might make calculation errors during the calculation process due to the complexity of abdication. This might be because they didn't have a good understanding of the calculation of abdication. For example, if 5 minus 6 wasn't enough, they had to retreat from 10 to 10, add it to the single digits, and then subtract. If 2 minus 7 wasn't enough, they had to retreat from 100 to 10. This series of calculations was not well understood, resulting in confusion. - In the teaching, although conventional methods such as vertical calculation were taught, some students might still be used to calculating in their own way. For example, there might be situations like counting fingers in the abdication of the number within 20. This reflected that the teaching method might not be fully adapted to the learning habits of all students. It was necessary to further explore how to guide students to master more efficient and accurate calculation methods. 2. ** The application of different calculation methods ** - There might be many calculation methods for continuous substitution. For example, for three-digit substitution, in addition to vertical calculation, students might also be guided to use methods such as number decomposition to calculate. However, during the teaching process, it might be found that students 'acceptance of different methods was different. Some students might prefer the more intuitive method of vertical calculation, but they might have difficulty understanding and applying other methods. This required thinking about how to balance the teaching of multiple calculation methods so that students could choose the appropriate method according to different topic situations. ** 2. Students 'performance in solving problems ** 1. ** Comprehension of the question ** - Students might not be able to understand the meaning of the questions in the application questions involving continuous substitution. For example, in a continuous deduction application question written according to some actual scenarios, such as the number of crops planted, the number of insects, etc., the student might have difficulty accurately determining which numbers have a deduction relationship, and thus list the wrong calculations. This might be because there was too much information in the questions, and students lacked the ability to extract key mathematical information from complex information. 2. ** Judgement of operational relationships ** - When students were solving problems, they would sometimes confuse the relationship between addition and substitution. For example, in some questions that required continuous deduction to get the answer, addition might be used incorrectly. This reflected that the students did not have a deep understanding of the significance of deduction in practical problems. They needed to strengthen it through more examples in teaching. ** 3. Other problems in the teaching process ** 1. ** Thought Guidance ** - When he was teaching the continuous deduction, he might not have fully explored the depth of the students 'thinking. For example, when guiding students to discover the rules in the continuous deduction formula, they might only be limited to the conventional observation direction, such as calculating from left to right in order. They were not guided to observe and think from different angles, such as the difference law between numbers and the change law of numbers on the digits, which was not conducive to cultivating students 'scattered thinking. 2. ** Use of teaching tools and resources ** - In the teaching process, the use of teaching aids (such as counters) or multi-media resources (such as coursewares) may not be sufficient or reasonable. For example, when explaining the continuous abdication process, the counter could have shown the abdication process very well, but it might not have played its full role in teaching, causing some students to have difficulty understanding the abstract concept of abdication. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

A fanfic about significant digits could be a story that somehow involves the concept of significant digits in a creative way. For example, it might be a science - fiction story where accurate measurements using significant digits are crucial for some kind of space travel or high - tech experiment. Maybe the characters are scientists or engineers who have to deal with the implications of significant digits in their work.

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I had 50 dollars. I spent 20 dollars on a book. So the subtraction story is 50 - 20 = 30. I have 30 dollars left.

It makes subtraction more interesting. Instead of just looking at numbers, students get to engage with a story, which is more fun. For example, a story about sharing toys can show subtraction in a natural way.

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Well, significant digits fanfiction could be about stories created by fans that somehow involve the concept of significant digits. Maybe it's in a scientific or mathematical setting where characters are dealing with precision and significant figures in a really creative way. For example, a story where a scientist is trying to solve a mystery that depends on accurately interpreting data with the right number of significant digits.

You can start by using real-life examples. Like, if you have five apples and eat two, how many are left? That makes it relatable and easier for kids to understand.