“先入”勿“為主”

李德強

我們先來看一個例子：

從1986年的自然教學大綱到2017年的小學科學課程標準，“溶解”一直都被列為學習內容，盡管不同階段對其學習的要求有一些變化，但認識溶解始終是重點。

從各種渠道收集了“溶解”內容的多個教學案例，發現在長達30年的教學發展中，這一課的“設計”并沒有太大的改變。其教學過程大致是這樣的：將一種物質放入水中（以食鹽為例），觀察并提出問題：食鹽到哪里去了？接下來研究食鹽是怎樣“不見的”。具體做法是將食鹽、石子、糖等物質放進水中，通過觀察、描述、比較其變化過程，初步形成“食鹽是怎樣不見的”的結論，然后借助有色物質（如高錳酸鉀）的溶解過程，仔細觀察其由“看得見的顆?！弊兂伞翱床灰姷奈⒘！钡倪^程，從而更進一步認識物質在水中的溶解。在課的最后，還會將多種物質的溶解狀況進行比較，在辨別中加深對溶解的理解。

上述流程基本是按照“觀察—比較—分析—抽象—概括”的過程展開的。在引導認識溶解現象的過程中，可謂步步為營，達成目標。從面上來看，并沒有什么大的問題，但如果仔細考問，就會發現其“先入”且“為主”的特征十分明顯。

在前述過程中，當學生講到“鹽看不見了”時，教師就會理所當然地采取與石子比較、借助有色物質的溶解過程來證明“鹽的確化成了看不見的微?！?。教師為什么會采取這些方式和方法來展開這一教學過程呢？其中一個主要原因就是，教師是知道在小學階段對溶解的描述的，其核心要點包括兩個方面：一是物質變成了看不見的微粒，另一個是這些微粒均勻地分散在水中。采用石子和有色物質作為對比材料正好對應了這兩點，這就是“先入”的知識起作用了，使得教師自然而然地牽著學生奔著這兩點知識而去，省掉了許多探究前的思維活動，比較順利地得到了溶解的概念。但從眾多辨別物質在水中是否溶解的情況來看，學生的認識其實是模棱兩可的，要么說不清楚，要么呆板地對照概念進行比較，“溶解”并沒有在學生的頭腦中真正建構起來，可見“為主”替代了學生的思維，使得探究實踐的價值“知識化”了。

那么，“先入”卻不“為主”的教學呈現可能是什么樣的呢？我們可以假想一下，如果教師自己也不知道“溶解”是怎么回事，當他和學生一起發現了“鹽在水中不見了”的現象時，他該如何運用自己的科學能力引導學生將探究實踐進行下去呢？或許，首先要想辦法證明鹽的確還在水中而不是跑到別處去了；其次要引導學生思考，“看不見的鹽”在水中會以一種什么樣的狀態存在呢？可以通過畫一畫、用模擬的顆粒擺一擺等多種形式提出自己的解釋，發表自己的觀點，但并不是你的觀點就能得到大家的認可，所以最后還得想辦法來證明自己觀點的合理性、正確性等，于是學生的探究實踐活動也就深入進去了，其自主性、能動性也就產生了。對于學生而言，能提出的觀點和想到的證明方法可能非常有限，這時就需要教師展現引導者作用了。

可見，“先入”且“為主”與“先入”卻不“為主”所產生的是兩種完全不一樣的教學路徑，前者往往過多地依賴自己已有的知識，將教學過程細化為得到既有結論的若干個環節，其目的就是奔著最后的結論而去的。后者則不一樣，是依據對現象的觀察，運用多種方式方法展開的探究實踐，其目的是尋求證據，建構觀點。從學科核心素養培養的角度看，“先入”卻不“為主”能讓教師走近學生的探究世界，看到他們的可能性、成長性。這不僅能激發學生的創新潛能，使教學變得智慧而生動，而且能使學生在科學觀念、科學思維、科學實踐等多方面得到良好發展。

Don’t be Preconceived

LI Deqiang

中圖分類號：G424文獻標識碼：ADOI：10.16400/j.cnki.kjdk.2021.24.003

LI Deqiang

Deputy Editor in Chief of Science Textbook of People’s Education Hubei Education Press

Vice Chairman of Primary School Science Teaching Steering Committee of Hubei Provincial Department of Edu‐cation

Excellent Expert in Yichang City， Hubei Province

Let’s take a look at an example：

From the nature syllabus in 1986 to the primary school science curriculum standard in 2017， "dissolu？ tion" has always been listed as the learning content. Although there are some changes in the learning re？ quirements at different stages， the understanding of dissolution has always been the focus.

Severalteachingcasesof"dissolving"content are collected from various channels. It is found that the "design" of this course has not changed much in the 30-year teaching development. The teaching pro？ cess is roughly like this： put a substance into water（take salt as an example）， observe and ask the ques？ tion： where is the salt？ Next， study how salt is "in？ visible". The specific method is to put salt， stone， sugar and other substances into water， preliminarily form the conclusion of "how salt is invisible" by ob？ serving， describing and comparing their change pro？ cess，andthencarefullyobservetheprocessfrom"visibleparticles"to"invisibleparticles"withthe help of the dissolution process of colored substances（such as potassium permanganate）， So as to further understand the dissolution of substances in water. At the end of the class， we will compare the dissolution of various substances to deepen the understanding of dissolution in discrimination.

The above process is basically carried out ac？ cordingtotheprocessof"observation-comparisonanalysis-abstraction-generalization". In the process of guiding the understanding of dissolution phenomenon， it can be said to achieve the goal step by step. Gen？ erally speaking， there is no big problem， but if you ask carefully， you will find that its "first in" and"main" characteristics are very obvious.

Intheaboveprocess，whenthestudentssay that "salt is invisible"， the teacher will naturally com？ pare it with stones and prove that "salt has indeed turned into invisible particles" with the help of the dissolutionprocessofcoloredsubstances.Whydo teachers adopt these ways and methods to carry out this teaching process？ One of the main reasons is that teachers know the description of dissolution in primary school， and its core points include two as？ pects： one is that substances become invisible parti？ cles， and the other is that these particles are evenly dispersed in water. The use of stones and colored ma？ terials as comparative materials just corresponds to these two points， which is that the "first in" knowl？ edge works， which makes the teacher naturally lead the students to run towards these two points of knowl？ edge， saves many thinking activities before explora？ tion， and obtains the concept of solution smoothly. However， judging from many situations of distinguish？ ing whether substances are dissolved in water， stu？ dents’ understanding is actually ambiguous， either un？ clear or rigid comparison with concepts. "Dissolution" is not really constructed in students’ minds. It can be seen that "main" replaces students’ thinking， mak？ ing the value of inquiry practice "intellectualized".

So what is the possible presentation of "first in" but not "main" teaching？ We can imagine that if the teacher doesn’t know what "dissolution" is， how can he use his scientific ability to guide the students to carry on the exploration practice when he and the students find the phenomenon of "salt missing in the water"？ Perhaps， first of all， we should find a way to prove that the salt is still in the water instead of go？ ing elsewhere； Secondly， we should guide students to think about what kind of state "invisible salt" will ex？ ist in water？ You can put forward your own explana？ tion and express your own views in various forms such as drawing a picture and using simulated parti？ cles to swing， but your views can not be recognized by everyone， so you have to find ways to prove the rationality and correctness of your views. Therefore， students’ exploration and practice activities will go deep into it， and their autonomy and initiative will be produced. For students， the ideas they can put for？ ward and the proof methods they can think of may be very limited. At this time， teachers need to show the role of guides.

It can be seen that "first in" and "main" and"first in" but not "main" produce two completely dif？ ferentteachingpaths.Theformeroftenreliestoo muchontheirexistingknowledgeandrefinesthe teaching process into several links to get the existing conclusion， with the purpose of running towards the final conclusion. The latter is different. It is an inqui？ ry practice based on the observation of phenomena and using various ways and methods. Its purpose is to seek evidence and construct views. From the per？ spective of discipline core quality training， "first in" but not "main" can let teachers approach students’ explorationworldandseetheirpossibilityand growth. This can not only stimulate students’ innova？ tive potential and make teaching intelligent and viv？ id， but also make students develop well in scientific concept， scientific thinking， scientific practice and so on.