facebook
favorite button
super instructor icon
معلم موثوق
يتميز هذا المعلم بمعدل استجابة سريع، مما يدل على خدمة عالية الجودة لطلابه.
member since icon
منذ سبتمبر 2022
أستاذ منذ سبتمبر 2022
repeat students icon
1 طالب منتظم
خيار موثوق لـ 1 طالب منتظم
SAT and ACT Tutoring / Exam Prep. All ages and skill levels.
course price icon
من 2750.17 EGP
arrow icon
I will tutor you in either the SAT (or PSAT) or the ACT, or both if you are studying for both. I've taken both tests multiple times and achieved top scores.
I can help with exam material (learning the math, english, and science), or coach you in taking it and provide more exam prep. Whatever your goal is, I'll do my best to help you with it.

All ages and levels welcome. I have experience with a variety of age groups and skill levels.
معلومات إضافية
Please let me know in advance if you have any specific goals you want to reach, or if you have any topics you would like to go through. This way I can prepare some material for our lesson.
المكان
location type icon
عبر الانترنت من الولايات المتحدة
من أنا؟
I'm studying two degrees, Aerospace engineering and Physics at Georgia Tech University in Atlanta. I will be able to help with any problems in the Physics SL/HL, Chemistry SL/HL, and Mathematics AA SL/HL curriculum, and will provide some exam technique to make you feel confident during your exams. I have also taken the SAT and ACT, achieving top scores in both exams.
What I can help with: Physics SL/HL, Math AA SL/HL, Chemistry SL/HL, SAT prep, ACT prep, lower level math, lower level physics, lower level chemistry.
I can tutor all ages and can help you with the specific goal(s) you want to reach!
المستوى التعليمي
Georgia Tech Institute - Aerospace Enginering and Physics in Atlanta, Georgia, USA. The British School in The Netherlands. Amity International school in Amsterdam.
الخبرة / المؤهلات
IBDP degree with 42 points , Mathematics AAHL 7 , PhysicsHL 7 , ChemistryHL 7, Economics 7, Dutch L&L 6, English L&L 6, and 2 TOK points.
السن
الأطفال (7-12 سنة)
شباب (13-17 سنة)
الكبار (18-64 سنة)
الكبار (65 سنة فأكثر)
مستوى الطالب
مبتدئ
متوسط
متقدم
المدة
60 دقيقة
الدرس يدور باللغة
الهولندية
الإنجليزية
الجاهزية في الأسبوع العادي
(GMT -05:00)
نيويورك
at teacher icon
على الانترنت عبر كاميرا ويب
Mon
Tue
Wed
Thu
Fri
Sat
Sun
00-04
04-08
08-12
12-16
16-20
20-24
I am Wolf (18 years old) and just completed the IB diploma with a 7 in math AA HL, a 7 for Physics HL and a 7 in Chemistry HL. Since I so recently graduated a lot of the content is still very fresh, but I am more than willing to go over the content again. I am currently attending at the University Georgia Tech Institute in Atlanta. I have 5 years of tutoring experience with various ages of students. I am able to tutor all levels of MYP math, physics and chemistry and the same for the DP program on HL. Looking at different methods to approach these problems and practicing your problem solving skills. I have experience in teaching and tutoring various international curricula, including IBDP,.
إقرأ المزيد
فصول مماثلة
arrow icon previousarrow icon next
verified badge
Experienced professor graduated from the Faculty. of Sciences and the Fac. of Medicine of France, gives private lessons in Mathematics - Analysis - Matrices - Statistics - Algebra - Physics - Chemistry - Biology of French, Quebec CEGEP or International programs (in English) to students of secondary classes, Terminales, Brevet Concours and classes university preparatory courses for the 2022/2023 academic year.
So that I can help students who take CNED and those who prepare for the SAT exams.
The lessons will take place either at home or online using a specific, very modernized method, a shared interactive board equipped with writing tools where I can, with the student, write and correct homework by exposing them directly, in addition to Zoom or Skype to communicate (very practical method like at home).
Results of my Terminale students since 2015: mentions Very good, Good and Excellent.
Contact me for more details.
verified badge
Need help with math? Do not search anymore ! I am here to help you overcome your difficulties and progress in this exciting subject. Whether you are in middle school, high school, or even university, my mathematics courses in French are suitable for all levels and all requirements.

With clear explanations and practical exercises, I will help you understand fundamental concepts and master the skills needed to succeed on your exams and assignments. From arithmetic to algebra, geometry and calculus, I cover a wide range of topics to meet your specific needs.

My classes are taught online via webcam, allowing you complete flexibility in your schedule. Whether you're at home or on the go, you can access quality lessons, taught in French, to help you achieve your academic goals.

Don't let math discourage you. Contact me today to book your first lesson and start building your maths confidence! 🌟📐

RAYEN
verified badge
🔢 Let's make math fun and rewarding for your child! Contact me now to schedule a session and unlock the door to mathematical success! 🚀
🌟 Why Choose My Math Tutoring?
-Tailored Learning: I understand that every child learns differently. I customize my teaching methods to suit your child's unique needs and learning style.
-Fun and Interactive: Math doesn't have to be boring! I incorporate games, puzzles, and interactive activities to make learning enjoyable and memorable.
-Proven Techniques: I recommend effective methods and tools that simplify complex math concepts. Your child will gain confidence and develop problem-solving skills that last a lifetime.
-Flexible Sessions: Whether your child needs a boost in understanding a specific concept or wants to stay ahead of the class, I offer flexible tutoring sessions to accommodate their schedule.
-Encouraging a Positive Mindset: I foster a positive attitude towards math, helping your child build confidence and enthusiasm for tackling challenges head-on.
verified badge
Hi there ! 👋

My name is Jamal and I am an experienced trainer, specialized in Maths and Physics-Chemistry courses, adapted to each student. 📚✨

✅ Improve your skills: Do you want to progress in Math, Physics-Chemistry, or both? I offer personalized courses for primary, middle and high school students, as well as for adults. 🧑‍🎓👩‍🎓

✅ All levels: No matter your level, even if you are a beginner, my courses are designed to help you progress! 🚀

✅ Effective teaching method: My method is based on an approach that facilitates the assimilation of concepts, allowing you to succeed in your homework and exams. 🎯 I combine theoretical courses, practical exercises, tutorials, exam corrections and revision sheets.

✅ Varied Support: I use a multitude of supports, including presentations, games, videos, images, audios, and homework between sessions to make learning dynamic. 🎥🎮📖

If you need help, feel free to contact me. I am here to help students around the world improve their grades and skills! 🌍💪
verified badge
This course aims to provide you with the knowledge and tools needed to better understand and master mathematics and physics. We offer personalized support to students of all specialties.

Sessions can be tailored to your specific needs, whether you are alone or in a group. We adjust the sessions according to your level and expectations.

Please do not hesitate to contact us if you have any questions.
verified badge
Teaching the entire mathematics curriculum to students from the third grade to the third preparatory grade, while following up on the student’s level and working on the lessons with which he faces difficulty in understanding, with a focus on the solution to master any skill that the student must master, you will feel the necessary confidence before entering the exam.
verified badge
I provide personalized support that highlights each student's strengths and develops effective study methods tailored to their pace and goals. My approach emphasizes progress, consistency, and self-confidence, enabling everyone to reach their full potential.

Thanks to structured and motivating support, several of my students have entered prestigious schools such as INSA, INP, EPFL, ECE or EM Lyon... These successes illustrate the impact of serious and results-oriented support.

With a clear methodology and rigorous monitoring, each student can achieve a lasting level of excellence.
verified badge
As a teaching professional, I have always enjoyed sharing my knowledge. My goal is to provide quality education. I am aware that some topics may seem complex, but often this is simply the result of an inadequate explanation by the teacher. With me, you will discover a real interest in the material!

We strive together to achieve academic excellence, overcoming the shortcomings and difficulties encountered by your child. Studies will become a pleasant experience for him. In addition to the courses, I can also help with school orientation, identifying their preferences and highlighting the advantages and benefits of a fulfilling educational ambition.

The sessions generally take place according to the following stages:

1️⃣ The first sessions are devoted to the assessment of the student's level in order to detect existing gaps.

2️⃣ Next, we create a personalized plan to address these gaps, including the number of hours of work needed, specific areas to focus on, and appropriate training and development exercises.

3️⃣ We stay in constant contact with the student's class teacher, to keep up to date with the latest requirements and ensure a consistent approach.

4️⃣ Subsequently, I provide exams similar to those that are likely to be asked in class, to prepare the student effectively.

5️⃣ Upon request, I write a regular report, usually monthly, to keep parents informed of their child's progress throughout their course.

I adapt my methodology according to the specific needs of each student, thus offering them a personalized and adapted work approach.

In addition, I offer crash courses for students preparing for the start of the school year, allowing them to start the year well prepared, with a solid lead on the school curriculum.

If you have any questions, do not hesitate to contact me. I will be happy to help you.
verified badge
I am an experienced teacher, particularly in academic support and homework monitoring, whether online or in person.
I provide private lessons for primary school four sessions per week (Math, Reading and comprehension, French, Written expression).
I am experienced in teaching the Arabic language to non-Arabic speakers using booklets known as the volume of Medina series...
verified badge
The SAT exam is one of the major steps you need to go through in your life; it's a step that is going to determine your college, your university, and your future as a whole. As with a lot of things in life, it can be a hard step, and there is no shame in asking for help. Here comes my role: I will help you overcome your problems and your difficulties. My job here is to help you achieve your desired results and unlock your potential. Simply put, we will go through every lesson, every unit, and every chapter. We will understand the concept of each lesson, with clear examples to follow. After each one, you will be tested, and after finishing your program, you will be tested on it. That's my plan for my students, so if you are interested, you can easily contact me.
verified badge
Ce cours s’adresse aux étudiants de toutes spécialités souhaitant :

°° Renforcer leurs bases en mathématiques, physique et sciences d’ingénieur.

°° Comprendre en profondeur les concepts clés.

°° Préparer efficacement leurs devoirs, contrôles et examens.


Pourquoi choisir ce cours ?

°° Méthodes pédagogiques adaptées à chaque élève.

°° Explications claires et simplifiées pour une compréhension rapide.

°° Résolution d’exercices types et aide personnalisée.

Modalités des cours :

•• Cours en ligne interactifs avec un suivi personnalisé.

•• Horaires flexibles pour s’adapter à votre emploi du temps.
verified badge
This course provides students with a solid foundation in mathematical concepts, problem-solving strategies, and critical thinking skills. Key topics include number operations, algebra, geometry, data analysis, and introductory functions. Students will develop fluency in mathematical reasoning and apply concepts to real-world situations, laying the groundwork for higher-level math and related disciplines. Emphasis is placed on conceptual understanding, procedural accuracy, and mathematical communication. This course is designed to strengthen core math skills and build confidence in both academic and everyday applications of mathematics.
verified badge
Vous êtes en Terminale, en prépa, en BUT, en Licence ou dans une formation où les mathématiques jouent un rôle clé ? Vous souhaitez renforcer vos bases, gagner en confiance, ou réussir vos examens et concours ?

Je propose des cours de mathématiques en ligne, entièrement personnalisés et spécialement adaptés aux niveaux avancés (Terminale → post-bac).

Fort de plus de 6 ans d’expérience en accompagnement, d’un parcours en Classe Prépa MPSI–MP et d’une formation en école d’ingénieur, j’explique les notions de manière claire, structurée et adaptée à chaque élève, même pour les chapitres les plus exigeants.

Mes cours sont interactifs, orientés vers :

la compréhension profonde des concepts,

la résolution d’exercices types et difficiles,

la méthodologie indispensable pour réussir les évaluations, partiels ou concours.

✔️ Avantages :

Explications adaptées aux exigences du niveau Terminale et supérieur

Flexibilité des horaires

Suivi personnalisé avec progression garantie

Aide aux DM, DS, révisions, examens, concours, et à la préparation du Bac de maths

🎯 Mon objectif : vous faire progresser efficacement et vous donner les outils pour exceller en mathématiques, quel que soit votre niveau actuel.
verified badge
I help students in Luxembourgish high schools succeed in the crucial mathematics exam. My approach focuses on past exam papers and official marking criteria.
1. Analysis & Differential Calculus (The core of the exam) Complex functions: Complete study of logarithmic and exponential functions. Limits and Continuity: Resolving indeterminates and using L'Hôpital's rule. Integral Calculus: Antiderivatives, integration by parts, and calculating areas/volumes.
2. Linear Algebra & Geometry (Luxembourg Specific) - Complex Numbers: Algebraic and trigonometric forms and solving equations in C. Analytical geometry of space: Vectors, planes, lines and intersections. Systems of equations: Gaussian elimination and geometric interpretation.
3. Probability & Combinatorics - Counting (arrangements, combinations). Probability laws (Binomial, Normal).
My online tutoring method - "Prep" exam correction: Specific work on in-class assignments (tests) to aim for the highest grade. Past exams: Step-by-step solutions to final exams from the last 5 years.
Interactive screen: Use of digital tools where I write the solutions to exercises and explanations of the lesson.
verified badge
Partie 1 : Réussite au Baccalauréat Luxembourgeois (Section B, C & IB)
Un accompagnement intensif pour transformer le stress de l'examen en mention "Très Bien".

Analyse de haut niveau : Maîtrise complète des fonctions (logarithmes, exponentielles) et du calcul intégral.

Géométrie & Algèbre : Systèmes de Gauss, nombres complexes et géométrie vectorielle dans l'espace.

Probabilités : Analyse combinatoire et lois de probabilité (Binomiale, Normale).

Méthodologie : Rédaction rigoureuse "zéro faute" pour maximiser les points aux examens nationaux.

Partie 2 : Soutien Universitaire (Bachelor & Licence)
Pour les étudiants en Économie, Ingénierie, Informatique ou Sciences Humaines.

Algèbre Linéaire : Espaces vectoriels, diagonalisation et applications matricielles.

Analyse Réelle : Suites, séries, développements limités et calcul différentiel.

Statistiques & Probabilités : Tests d'hypothèses, régressions et estimation de paramètres.
message icon
اتصل بWolf
repeat students icon
الدرس الأول مضمون
بواسطة
ضمان المدرس المناسب
فصول مماثلة
arrow icon previousarrow icon next
verified badge
Experienced professor graduated from the Faculty. of Sciences and the Fac. of Medicine of France, gives private lessons in Mathematics - Analysis - Matrices - Statistics - Algebra - Physics - Chemistry - Biology of French, Quebec CEGEP or International programs (in English) to students of secondary classes, Terminales, Brevet Concours and classes university preparatory courses for the 2022/2023 academic year.
So that I can help students who take CNED and those who prepare for the SAT exams.
The lessons will take place either at home or online using a specific, very modernized method, a shared interactive board equipped with writing tools where I can, with the student, write and correct homework by exposing them directly, in addition to Zoom or Skype to communicate (very practical method like at home).
Results of my Terminale students since 2015: mentions Very good, Good and Excellent.
Contact me for more details.
verified badge
Need help with math? Do not search anymore ! I am here to help you overcome your difficulties and progress in this exciting subject. Whether you are in middle school, high school, or even university, my mathematics courses in French are suitable for all levels and all requirements.

With clear explanations and practical exercises, I will help you understand fundamental concepts and master the skills needed to succeed on your exams and assignments. From arithmetic to algebra, geometry and calculus, I cover a wide range of topics to meet your specific needs.

My classes are taught online via webcam, allowing you complete flexibility in your schedule. Whether you're at home or on the go, you can access quality lessons, taught in French, to help you achieve your academic goals.

Don't let math discourage you. Contact me today to book your first lesson and start building your maths confidence! 🌟📐

RAYEN
verified badge
🔢 Let's make math fun and rewarding for your child! Contact me now to schedule a session and unlock the door to mathematical success! 🚀
🌟 Why Choose My Math Tutoring?
-Tailored Learning: I understand that every child learns differently. I customize my teaching methods to suit your child's unique needs and learning style.
-Fun and Interactive: Math doesn't have to be boring! I incorporate games, puzzles, and interactive activities to make learning enjoyable and memorable.
-Proven Techniques: I recommend effective methods and tools that simplify complex math concepts. Your child will gain confidence and develop problem-solving skills that last a lifetime.
-Flexible Sessions: Whether your child needs a boost in understanding a specific concept or wants to stay ahead of the class, I offer flexible tutoring sessions to accommodate their schedule.
-Encouraging a Positive Mindset: I foster a positive attitude towards math, helping your child build confidence and enthusiasm for tackling challenges head-on.
verified badge
Hi there ! 👋

My name is Jamal and I am an experienced trainer, specialized in Maths and Physics-Chemistry courses, adapted to each student. 📚✨

✅ Improve your skills: Do you want to progress in Math, Physics-Chemistry, or both? I offer personalized courses for primary, middle and high school students, as well as for adults. 🧑‍🎓👩‍🎓

✅ All levels: No matter your level, even if you are a beginner, my courses are designed to help you progress! 🚀

✅ Effective teaching method: My method is based on an approach that facilitates the assimilation of concepts, allowing you to succeed in your homework and exams. 🎯 I combine theoretical courses, practical exercises, tutorials, exam corrections and revision sheets.

✅ Varied Support: I use a multitude of supports, including presentations, games, videos, images, audios, and homework between sessions to make learning dynamic. 🎥🎮📖

If you need help, feel free to contact me. I am here to help students around the world improve their grades and skills! 🌍💪
verified badge
This course aims to provide you with the knowledge and tools needed to better understand and master mathematics and physics. We offer personalized support to students of all specialties.

Sessions can be tailored to your specific needs, whether you are alone or in a group. We adjust the sessions according to your level and expectations.

Please do not hesitate to contact us if you have any questions.
verified badge
Teaching the entire mathematics curriculum to students from the third grade to the third preparatory grade, while following up on the student’s level and working on the lessons with which he faces difficulty in understanding, with a focus on the solution to master any skill that the student must master, you will feel the necessary confidence before entering the exam.
verified badge
I provide personalized support that highlights each student's strengths and develops effective study methods tailored to their pace and goals. My approach emphasizes progress, consistency, and self-confidence, enabling everyone to reach their full potential.

Thanks to structured and motivating support, several of my students have entered prestigious schools such as INSA, INP, EPFL, ECE or EM Lyon... These successes illustrate the impact of serious and results-oriented support.

With a clear methodology and rigorous monitoring, each student can achieve a lasting level of excellence.
verified badge
As a teaching professional, I have always enjoyed sharing my knowledge. My goal is to provide quality education. I am aware that some topics may seem complex, but often this is simply the result of an inadequate explanation by the teacher. With me, you will discover a real interest in the material!

We strive together to achieve academic excellence, overcoming the shortcomings and difficulties encountered by your child. Studies will become a pleasant experience for him. In addition to the courses, I can also help with school orientation, identifying their preferences and highlighting the advantages and benefits of a fulfilling educational ambition.

The sessions generally take place according to the following stages:

1️⃣ The first sessions are devoted to the assessment of the student's level in order to detect existing gaps.

2️⃣ Next, we create a personalized plan to address these gaps, including the number of hours of work needed, specific areas to focus on, and appropriate training and development exercises.

3️⃣ We stay in constant contact with the student's class teacher, to keep up to date with the latest requirements and ensure a consistent approach.

4️⃣ Subsequently, I provide exams similar to those that are likely to be asked in class, to prepare the student effectively.

5️⃣ Upon request, I write a regular report, usually monthly, to keep parents informed of their child's progress throughout their course.

I adapt my methodology according to the specific needs of each student, thus offering them a personalized and adapted work approach.

In addition, I offer crash courses for students preparing for the start of the school year, allowing them to start the year well prepared, with a solid lead on the school curriculum.

If you have any questions, do not hesitate to contact me. I will be happy to help you.
verified badge
I am an experienced teacher, particularly in academic support and homework monitoring, whether online or in person.
I provide private lessons for primary school four sessions per week (Math, Reading and comprehension, French, Written expression).
I am experienced in teaching the Arabic language to non-Arabic speakers using booklets known as the volume of Medina series...
verified badge
The SAT exam is one of the major steps you need to go through in your life; it's a step that is going to determine your college, your university, and your future as a whole. As with a lot of things in life, it can be a hard step, and there is no shame in asking for help. Here comes my role: I will help you overcome your problems and your difficulties. My job here is to help you achieve your desired results and unlock your potential. Simply put, we will go through every lesson, every unit, and every chapter. We will understand the concept of each lesson, with clear examples to follow. After each one, you will be tested, and after finishing your program, you will be tested on it. That's my plan for my students, so if you are interested, you can easily contact me.
verified badge
Ce cours s’adresse aux étudiants de toutes spécialités souhaitant :

°° Renforcer leurs bases en mathématiques, physique et sciences d’ingénieur.

°° Comprendre en profondeur les concepts clés.

°° Préparer efficacement leurs devoirs, contrôles et examens.


Pourquoi choisir ce cours ?

°° Méthodes pédagogiques adaptées à chaque élève.

°° Explications claires et simplifiées pour une compréhension rapide.

°° Résolution d’exercices types et aide personnalisée.

Modalités des cours :

•• Cours en ligne interactifs avec un suivi personnalisé.

•• Horaires flexibles pour s’adapter à votre emploi du temps.
verified badge
This course provides students with a solid foundation in mathematical concepts, problem-solving strategies, and critical thinking skills. Key topics include number operations, algebra, geometry, data analysis, and introductory functions. Students will develop fluency in mathematical reasoning and apply concepts to real-world situations, laying the groundwork for higher-level math and related disciplines. Emphasis is placed on conceptual understanding, procedural accuracy, and mathematical communication. This course is designed to strengthen core math skills and build confidence in both academic and everyday applications of mathematics.
verified badge
Vous êtes en Terminale, en prépa, en BUT, en Licence ou dans une formation où les mathématiques jouent un rôle clé ? Vous souhaitez renforcer vos bases, gagner en confiance, ou réussir vos examens et concours ?

Je propose des cours de mathématiques en ligne, entièrement personnalisés et spécialement adaptés aux niveaux avancés (Terminale → post-bac).

Fort de plus de 6 ans d’expérience en accompagnement, d’un parcours en Classe Prépa MPSI–MP et d’une formation en école d’ingénieur, j’explique les notions de manière claire, structurée et adaptée à chaque élève, même pour les chapitres les plus exigeants.

Mes cours sont interactifs, orientés vers :

la compréhension profonde des concepts,

la résolution d’exercices types et difficiles,

la méthodologie indispensable pour réussir les évaluations, partiels ou concours.

✔️ Avantages :

Explications adaptées aux exigences du niveau Terminale et supérieur

Flexibilité des horaires

Suivi personnalisé avec progression garantie

Aide aux DM, DS, révisions, examens, concours, et à la préparation du Bac de maths

🎯 Mon objectif : vous faire progresser efficacement et vous donner les outils pour exceller en mathématiques, quel que soit votre niveau actuel.
verified badge
I help students in Luxembourgish high schools succeed in the crucial mathematics exam. My approach focuses on past exam papers and official marking criteria.
1. Analysis & Differential Calculus (The core of the exam) Complex functions: Complete study of logarithmic and exponential functions. Limits and Continuity: Resolving indeterminates and using L'Hôpital's rule. Integral Calculus: Antiderivatives, integration by parts, and calculating areas/volumes.
2. Linear Algebra & Geometry (Luxembourg Specific) - Complex Numbers: Algebraic and trigonometric forms and solving equations in C. Analytical geometry of space: Vectors, planes, lines and intersections. Systems of equations: Gaussian elimination and geometric interpretation.
3. Probability & Combinatorics - Counting (arrangements, combinations). Probability laws (Binomial, Normal).
My online tutoring method - "Prep" exam correction: Specific work on in-class assignments (tests) to aim for the highest grade. Past exams: Step-by-step solutions to final exams from the last 5 years.
Interactive screen: Use of digital tools where I write the solutions to exercises and explanations of the lesson.
verified badge
Partie 1 : Réussite au Baccalauréat Luxembourgeois (Section B, C & IB)
Un accompagnement intensif pour transformer le stress de l'examen en mention "Très Bien".

Analyse de haut niveau : Maîtrise complète des fonctions (logarithmes, exponentielles) et du calcul intégral.

Géométrie & Algèbre : Systèmes de Gauss, nombres complexes et géométrie vectorielle dans l'espace.

Probabilités : Analyse combinatoire et lois de probabilité (Binomiale, Normale).

Méthodologie : Rédaction rigoureuse "zéro faute" pour maximiser les points aux examens nationaux.

Partie 2 : Soutien Universitaire (Bachelor & Licence)
Pour les étudiants en Économie, Ingénierie, Informatique ou Sciences Humaines.

Algèbre Linéaire : Espaces vectoriels, diagonalisation et applications matricielles.

Analyse Réelle : Suites, séries, développements limités et calcul différentiel.

Statistiques & Probabilités : Tests d'hypothèses, régressions et estimation de paramètres.
ضمان المدرس المناسب
favorite button
message icon
اتصل بWolf