Content Developer Guide for teachers


    The teacher can use the dashed-wedged representation to express stereochemistry in a structure. In the case the teacher draws the expected correct structure with dashed-wedged bonds, the student is also expected to draw the answer with dashed-wedged bonds. In the case the teacher draws the structures with simple bond-line drawing, the student can use the simple bond-line drawing in the answer, but the dashed-wedged representation is also accepted.

    In case of exercise types that require relative stereochemistry in the answer, the expected answer should contain the 'or1' notation, so we don't exclude any of the correct answers. (The cause of this is that the notation cis and trans can correspond with two absolute configurations) Stereo1

    Example: Draw trans-1,2-dimethylcyclohexane! Both answer should be accepted from the student:

    Stereo2 Stereo3

    The teacher should draw the correct answer with the following notation:


    Lone pairs

    The teacher can expect drawing of lone pairs or single electrons from the students. Lone pairs and single electrons, specified by the teacher on the expected correct structure, are expected from the students to draw exactly the same way. In the case the teacher doesn't specify any lone pairs or electrons on the expected correct structure, only those lone pairs and single electrons are accepted in the answer which are correctly drawn by the student.

    Hydrogen atoms

    Zosimos doesn't check Hydrogen atoms in the answer of the student at the moment.

    Drawing options

    The teacher can set the chemical editor preferences in questions and answers. The student will use the settings defined by the teacher during the completion of the exercise. The following visualisation options are available:

    • Molecule drawing style: Skeletal, Structural, Implicit hydrogens on terminals and heteroatoms, Heavy atom and explicit hydrogen labels, Heteroatoms and explicit hydrogen labels.
    • Numbering on atoms
    • Coloring by atom types

    Unspecified stereocenters

    The teacher will receive a warning when Zosimos detects unspecified stereocenters in the expected correct answer where the evaluation is not yet implemented in Zosimos. For example:


    In this case, all structures with the same connectivity will be accepted. Certain projections, such as Fischer type are not yet supported.

    Cis-trans isomers

    The teacher can ask the student to draw the cis or trans isomers of a structure. For example:


    However, if the teacher would like to accept both cis and trans isomer of a structure in the students' answer, the teacher has to apply a special drawing style. For example:


    The teacher has to draw the correct structure in one line:



    At the moment, only one-step reactions are supported in Zosimos. We recommend creating exercises where you ask for an extension of a single step reaction. Evaluation might fail because of dislocation of reactants or drawing reactions not in-line. If the students are trained in drawing in MarvinJS, the teacher can expect the whole reaction.


    Reaction mechanism and resonances

    The tool for drawing the curved arrows in reaction mechanism and resonances is the electron flow arrow on the left toolbar of the drawing tool.

    There are two options to draw the curved arrows when the teacher creates new exercises:

    • Direct arrow option: simple electron pushing representation with a curved arrow.
    • Show forming bond option: complex electron pushing representation with a curved arrow and a dotted line is drawn to the forming bond.

    These options are available under the Exercise settings button for teachers when creating new exercises.

    Curved arrow preference settings

    The default option is always the Direct arrow drawing style when creating a new exercise. The teacher needs to set the curved arrow preferences to use the Show forming bond style in each exercise on demand. Exercises in duplicated quizzes will keep their original settings.
    The students' drawing tool is set to the same curved arrow drawing style that the teacher set in the Exercise settings.

    Any questions? Please email our team at and we will be happy to help you!