diff --git a/src/app/authentication/auth.service.ts b/src/app/authentication/auth.service.ts
index b59bb38..24ac133 100644
--- a/src/app/authentication/auth.service.ts
+++ b/src/app/authentication/auth.service.ts
@@ -2,7 +2,7 @@ import {inject, Injectable} from '@angular/core';
 import {HttpClient, HttpResponse} from "@angular/common/http";
 import {environment} from "../../environments/environment";
 import {map, Observable, of} from "rxjs";
-import {LoginDTO} from "../DTO/DTOList";
+import {LoginDTO, LoginToken} from "../DTO/DTOList";
 import {StatusMessageResponse} from "../DTO/StatusMessageResponse";
 import {ExecutionStatus} from "../enums/ExecutionStatus";
 
@@ -28,7 +28,7 @@ export class AuthService {
             // Check response body if it is valid
             if (response.body) {
               const message = response.body;
-              if (message?.status == ExecutionStatus.VALID) {
+              if (message?.status === ExecutionStatus.VALID) {
                 return of(true);
               }
             }
@@ -43,9 +43,9 @@ export class AuthService {
     return false;
   }
 
-  login(login: LoginDTO): Observable<HttpResponse<LoginDTO | StatusMessageResponse>> {
+  login(login: LoginDTO): Observable<HttpResponse<LoginToken | StatusMessageResponse>> {
     console.log("Requesting login to " + this.loginUrl);
-    return this.http.post<LoginDTO | StatusMessageResponse>(this.loginUrl, login, {
+    return this.http.post<LoginToken | StatusMessageResponse>(this.loginUrl, login, {
       responseType: 'json',
       observe: 'response'
     });
diff --git a/src/app/authentication/login/auth.component.ts b/src/app/authentication/login/auth.component.ts
index 763d957..0991dab 100644
--- a/src/app/authentication/login/auth.component.ts
+++ b/src/app/authentication/login/auth.component.ts
@@ -16,6 +16,7 @@ import {Router} from "@angular/router";
 import {TeacherService} from "../../services/teacher/teacher.service";
 import {Roles} from "../../enums/Roles";
 import {Teacher} from "../../DTO/TeacherDTO";
+import {StatusMessageResponse} from "../../DTO/StatusMessageResponse";
 
 @Component({
   selector: 'app-login',
@@ -74,10 +75,10 @@ export class AuthComponent {
       console.log("Logging in");
       // Check if status code 200
       this.loginService.login(loginData).pipe(
-        map((response: HttpResponse<any>) => {
+        map((response: HttpResponse<LoginToken | StatusMessageResponse>) => {
           console.log("Login successful");
           // Get token
-          const loginToken: LoginToken = response.body;
+          const loginToken: LoginToken = response.body as LoginToken;
 
           // Show alert message
           this.alert.open("Login successful", "Close");
diff --git a/src/app/components/top-header/top-header.component.ts b/src/app/components/top-header/top-header.component.ts
index ab6b34b..e6f13eb 100644
--- a/src/app/components/top-header/top-header.component.ts
+++ b/src/app/components/top-header/top-header.component.ts
@@ -36,7 +36,7 @@ import {NgOptimizedImage} from "@angular/common";
 })
 export class TopHeaderComponent implements OnInit {
   @Input()
-  public sidenav: MatDrawer | any;
+  public sidenav: MatDrawer | undefined;
 
   @Output()
   public readonly sectionSelected: EventEmitter<number> = new EventEmitter<number>();
diff --git a/src/app/dashboard/admin/admin-dashboard/admin-dashboard.component.ts b/src/app/dashboard/admin/admin-dashboard/admin-dashboard.component.ts
index 24fb6c3..a046be8 100644
--- a/src/app/dashboard/admin/admin-dashboard/admin-dashboard.component.ts
+++ b/src/app/dashboard/admin/admin-dashboard/admin-dashboard.component.ts
@@ -91,7 +91,7 @@ export class AdminDashboardComponent implements OnInit {
   protected displayedColumns: string[] = ['name', 'grade', 'section', 'time', 'date', 'status'];
   protected recentActivitiesRow: RecentActivitiesRow[] = [
   ];
-  protected recentActivitiesTableDataSource: MatTableDataSource<any> = new MatTableDataSource(this.recentActivitiesRow);
+  protected recentActivitiesTableDataSource: MatTableDataSource<RecentActivitiesRow> = new MatTableDataSource(this.recentActivitiesRow);
 
 
   constructor() {
diff --git a/src/app/dashboard/announcements/announcements.component.ts b/src/app/dashboard/announcements/announcements.component.ts
index 0427ea6..880c7f5 100644
--- a/src/app/dashboard/announcements/announcements.component.ts
+++ b/src/app/dashboard/announcements/announcements.component.ts
@@ -93,7 +93,7 @@ export class AnnouncementsComponent implements OnInit {
 
   // Mat Table data
   displayedColumns: string[] = ['title', 'status', 'viewers'];
-  announcementTableDataSource: MatTableDataSource<any> = new MatTableDataSource(this.announcements);
+  announcementTableDataSource: MatTableDataSource<{}> = new MatTableDataSource(this.announcements);
 
   // Announcement Pagination
   // Pagination info
diff --git a/src/app/dashboard/teacher/teacher-dashboard/teacher-dashboard.component.ts b/src/app/dashboard/teacher/teacher-dashboard/teacher-dashboard.component.ts
index 676abbb..df2db67 100644
--- a/src/app/dashboard/teacher/teacher-dashboard/teacher-dashboard.component.ts
+++ b/src/app/dashboard/teacher/teacher-dashboard/teacher-dashboard.component.ts
@@ -94,7 +94,7 @@ export class TeacherDashboardComponent implements OnInit, OnChanges {
   // Recent Activities table and Data Source
   protected displayedColumns: string[] = ['name', 'grade', 'section', 'time', 'date', 'status'];
   protected recentActivitiesRow: RecentActivitiesRow[] = [];
-  protected recentActivitiesTableDataSource: MatTableDataSource<any> = new MatTableDataSource(this.recentActivitiesRow);
+  protected recentActivitiesTableDataSource: MatTableDataSource<RecentActivitiesRow> = new MatTableDataSource(this.recentActivitiesRow);
 
   // Section
   @Input()
@@ -384,9 +384,11 @@ export class TeacherDashboardComponent implements OnInit, OnChanges {
   }
 
   updateAttendanceOverviewData(label: string[], data: number[], dataset = 0) {
-    this.attendanceOverviewChart.data.labels = label;
-    this.attendanceOverviewChart.data.datasets[dataset].data = data;
-    this.attendanceOverviewChart.update();
+    if (this.attendanceOverviewChart !== undefined) {
+      this.attendanceOverviewChart.data.labels = label;
+      this.attendanceOverviewChart.data.datasets[dataset].data = data;
+      this.attendanceOverviewChart.update();
+    }
   }
 
   updateDashboardStatistics() {
diff --git a/src/app/dashboard/teacher/teacher-students/teacher-students.component.ts b/src/app/dashboard/teacher/teacher-students/teacher-students.component.ts
index da41e77..553f3f8 100644
--- a/src/app/dashboard/teacher/teacher-students/teacher-students.component.ts
+++ b/src/app/dashboard/teacher/teacher-students/teacher-students.component.ts
@@ -49,7 +49,7 @@ export class TeacherStudentsComponent implements OnInit {
   // Pie Chart with Chart JS
   public pieChartLabels = ["Male", "Female"];
   public pieChartData = [512, 235];
-  public pieChart: any;
+  public pieChart: Chart<"pie", number[], string> | undefined;
 
   ngOnInit() {
     this.pieChart = new Chart('pieChart', {
diff --git a/src/app/services/attendance/attendance.service.ts b/src/app/services/attendance/attendance.service.ts
index d227189..f59b7eb 100644
--- a/src/app/services/attendance/attendance.service.ts
+++ b/src/app/services/attendance/attendance.service.ts
@@ -1,10 +1,11 @@
 import {inject, Injectable} from '@angular/core';
 import {environment} from "../../../environments/environment";
-import {HttpClient} from "@angular/common/http";
+import {HttpClient, HttpResponse} from "@angular/common/http";
 import {DateRange, Status} from "../../DTO/DTOList";
 import {Observable} from "rxjs";
 import {CountDTO} from "../../DTO/CountDTO";
 import {SortDirection} from "../../enums/SortDirection";
+import {AttendancePaging} from "../../DTO/AttendanceDTO";
 
 @Injectable({
   providedIn: 'root'
@@ -14,24 +15,21 @@ export class AttendanceService {
   apiUrl: string = environment.apiUrl + "/api/v1/attendances";
   http: HttpClient = inject(HttpClient);
 
-  constructor() {
-  }
-
-  countAttendance(dateRange: DateRange, status: Status): Observable<any> {
-    return this.http.post(this.apiUrl + `/status/${status}/date-range`, dateRange, {
+  countAttendance(dateRange: DateRange, status: Status): Observable<HttpResponse<number>> {
+    return this.http.post<number>(this.apiUrl + `/status/${status}/date-range`, dateRange, {
       observe: 'response',
       responseType: 'json'
     });
   }
 
-  countAttendanceInSectionByDateRange(sectionId: number, dateRange: DateRange, status: Status): Observable<any> {
+  countAttendanceInSectionByDateRange(sectionId: number, dateRange: DateRange, status: Status) {
     return this.http.post(this.apiUrl + `/status/${status}/section/${sectionId}/date-range`, dateRange, {
       observe: 'response',
       responseType: 'json'
     });
   }
 
-  countAttendanceInSectionByDate(sectionId: number, date: Date, status: Status): Observable<any> {
+  countAttendanceInSectionByDate(sectionId: number, date: Date, status: Status): Observable<HttpResponse<CountDTO>> {
     const formattedDate: string = date.toISOString().split('T')[0];
     return this.http.get<CountDTO>(this.apiUrl + `/status/${status}/section/${sectionId}/date?date=${formattedDate}`, {
       observe: 'response',
@@ -39,10 +37,10 @@ export class AttendanceService {
     });
   }
 
-  getAllSectionAndGradeLevelAttendanceByDate(sectionId: number, gradeLevelId: number, date: Date, page: number, size: number, sortBy = "date", orderBy: SortDirection = SortDirection.ASC): Observable<any> {
+  getAllSectionAndGradeLevelAttendanceByDate(sectionId: number, gradeLevelId: number, date: Date, page: number, size: number, sortBy = "date", orderBy: SortDirection = SortDirection.ASC): Observable<HttpResponse<AttendancePaging>> {
     const formattedDate = date.toISOString().split('T')[0];
 
-    return this.http.get(this.apiUrl + `/statistics/section/${sectionId}/grade-level/${gradeLevelId}/date`, {
+    return this.http.get<AttendancePaging>(this.apiUrl + `/statistics/section/${sectionId}/grade-level/${gradeLevelId}/date`, {
       params: {
         date: formattedDate,
         page: page,
diff --git a/src/app/services/charts/attendance/attendance-line-chart.service.ts b/src/app/services/charts/attendance/attendance-line-chart.service.ts
index 986f04e..0deaaba 100644
--- a/src/app/services/charts/attendance/attendance-line-chart.service.ts
+++ b/src/app/services/charts/attendance/attendance-line-chart.service.ts
@@ -1,7 +1,7 @@
 import {inject, Injectable} from '@angular/core';
 import {environment} from "../../../../environments/environment";
-import {HttpClient} from "@angular/common/http";
-import {DateRange, Status} from "../../../DTO/DTOList";
+import {HttpClient, HttpResponse} from "@angular/common/http";
+import {DateRange, LineChartDTO, Status} from "../../../DTO/DTOList";
 import {Observable} from "rxjs";
 
 @Injectable({
@@ -12,11 +12,11 @@ export class AttendanceLineChartService {
   private baseUrl: string = environment.apiUrl;
   private http: HttpClient = inject(HttpClient);
 
-  getAttendanceLineChart(status: Status, dateRange: DateRange): Observable<any> {
-    return this.http.post(`${this.baseUrl}/api/v1/attendances/graphic-organizers/line-chart?status=${status}`, dateRange, {observe: 'response', responseType: 'json'});
+  getAttendanceLineChart(status: Status, dateRange: DateRange): Observable<HttpResponse<LineChartDTO>> {
+    return this.http.post<LineChartDTO>(`${this.baseUrl}/api/v1/attendances/graphic-organizers/line-chart?status=${status}`, dateRange, {observe: 'response', responseType: 'json'});
   }
 
-  getSectionAttendanceLineChart(sectionId: number, status: Status, dateRange: DateRange): Observable<any> {
-    return this.http.post(`${this.baseUrl}/api/v1/attendances/graphic-organizers/sections/${sectionId}/line-chart?status=${status}`, dateRange, {observe: 'response', responseType: 'json'});
+  getSectionAttendanceLineChart(sectionId: number, status: Status, dateRange: DateRange): Observable<HttpResponse<LineChartDTO>> {
+    return this.http.post<LineChartDTO>(`${this.baseUrl}/api/v1/attendances/graphic-organizers/sections/${sectionId}/line-chart?status=${status}`, dateRange, {observe: 'response', responseType: 'json'});
   }
 }
diff --git a/src/app/services/section/section.service.ts b/src/app/services/section/section.service.ts
index eb74828..722652c 100644
--- a/src/app/services/section/section.service.ts
+++ b/src/app/services/section/section.service.ts
@@ -1,9 +1,10 @@
 import {inject, Injectable} from '@angular/core';
 import {environment} from "../../../environments/environment";
-import {HttpClient} from "@angular/common/http";
+import {HttpClient, HttpResponse} from "@angular/common/http";
 import {Observable} from "rxjs";
 import {Section} from "../../DTO/SectionDTO";
 import {SortDirection} from "../../enums/SortDirection";
+import {StatusMessageResponse} from "../../DTO/StatusMessageResponse";
 
 @Injectable({
   providedIn: 'root'
@@ -13,27 +14,15 @@ export class SectionService {
   private apiUrl: string = environment.apiUrl + "/api/v1/sections";
   private http: HttpClient = inject(HttpClient);
 
-  public createSection(section: Section) {
-    return this.http.post(this.apiUrl + "/create", section, {responseType: 'json', observe: 'response'});
+  public createSection(section: Section): Observable<HttpResponse<StatusMessageResponse>> {
+    return this.http.post<StatusMessageResponse>(this.apiUrl + "/create", section, {responseType: 'json', observe: 'response'});
   }
 
-  public updateSection(sectionId: number, section: Section) {
-    return this.http.put(this.apiUrl + `/${sectionId}`, section, {responseType: 'json', observe: 'response'});
+  public updateSection(sectionId: number, section: Section): Observable<HttpResponse<StatusMessageResponse>> {
+    return this.http.put<StatusMessageResponse>(this.apiUrl + `/${sectionId}`, section, {responseType: 'json', observe: 'response'});
   }
-
-  public updateSectionTeacher(sectionId: number, teacherId: number) {
-    return this.http.patch(this.apiUrl + `/${sectionId}/teacher`, {
-      params: {
-        sectionId: sectionId,
-        teacherId: teacherId
-      },
-      responseType: 'json',
-      observe: 'response'
-    });
-  }
-
-  public updateSectionGradeLevel(sectionId: number, gradeLevelId: number) {
-    return this.http.patch(this.apiUrl + `/${sectionId}/grade-level`, {
+  public updateSectionGradeLevel(sectionId: number, gradeLevelId: number): Observable<StatusMessageResponse> {
+    return this.http.patch<StatusMessageResponse>(this.apiUrl + `/${sectionId}/grade-level`, {
       params: {
         gradeLevelId: gradeLevelId
       },
@@ -42,8 +31,8 @@ export class SectionService {
     });
   }
 
-  public updateSectionName(sectionId: number, name: string) {
-    return this.http.patch(this.apiUrl + `/${sectionId}/name`, null, {
+  public updateSectionName(sectionId: number, name: string): Observable<HttpResponse<StatusMessageResponse>> {
+    return this.http.patch<StatusMessageResponse>(this.apiUrl + `/${sectionId}/name`, null, {
       params: {
         name: name
       },
@@ -52,15 +41,15 @@ export class SectionService {
     });
   }
 
-  public deleteSection(sectionId: number) {
-    return this.http.delete(this.apiUrl + `/${sectionId}`, {
+  public deleteSection(sectionId: number): Observable<HttpResponse<StatusMessageResponse>> {
+    return this.http.delete<StatusMessageResponse>(this.apiUrl + `/${sectionId}`, {
         responseType: 'json',
         observe: 'response'
       }
     );
   }
 
-  public getAllSectionsNoPaging() {
+  public getAllSectionsNoPaging(): Observable<HttpResponse<Section[]>> {
     return this.http.get<Section[]>(this.apiUrl + "/all", {
       params: {
         noPaging: true
@@ -70,7 +59,7 @@ export class SectionService {
     });
   }
 
-  public getAllSections(page: number, size: number, orderBy: SortDirection = SortDirection.ASC, sortBy = "sectionName"): Observable<any> {
+  public getAllSections(page: number, size: number, orderBy: SortDirection = SortDirection.ASC, sortBy = "sectionName") {
     return this.http.get(this.apiUrl + "/all", {
       params: {
         page: page,
@@ -83,7 +72,7 @@ export class SectionService {
     });
   }
 
-  public getSectionById(sectionId: number): Observable<any> {
+  public getSectionById(sectionId: number) {
     return this.http.get(this.apiUrl + `/${sectionId}`, {responseType: 'json', observe: 'response'});
   }
 
diff --git a/src/app/services/student/student.service.ts b/src/app/services/student/student.service.ts
index 27863a2..45e6e88 100644
--- a/src/app/services/student/student.service.ts
+++ b/src/app/services/student/student.service.ts
@@ -33,15 +33,15 @@ export class StudentService {
     })
   }
 
-  countStudentsBySection(sectionId: number) {
+  countStudentsBySection(sectionId: number): Observable<HttpResponse<CountDTO>> {
     return this.http.get<CountDTO>(this.apiUrl + `/api/v1/students/statistics/section?section=${sectionId}`, {
       observe: 'response',
       responseType: 'json'
     });
   }
 
-  public getAllStudents(page: number, size: number): Observable<any> {
-    return this.http.get(this.apiUrl + `/api/v1/students/all?page=${page}&size=${size}`);
+  public getAllStudents(page: number, size: number): Observable<StudentPaging> {
+    return this.http.get<StudentPaging>(this.apiUrl + `/api/v1/students/all?page=${page}&size=${size}`);
   }
 
   public createStudent(student: Student): Observable<HttpResponse<StatusMessageResponse>> {
@@ -137,8 +137,4 @@ export class StudentService {
       }
     });
   }
-
-  public isStudent(obj: any): obj is Student {
-    return 'id' in obj && 'name' in obj; // replace 'id' and 'name' with actual properties of Student
-  }
 }
diff --git a/src/app/services/teacher/teacher.service.ts b/src/app/services/teacher/teacher.service.ts
index 481c1ab..5d9e7d1 100644
--- a/src/app/services/teacher/teacher.service.ts
+++ b/src/app/services/teacher/teacher.service.ts
@@ -1,7 +1,8 @@
 import {inject, Injectable} from '@angular/core';
 import {environment} from "../../../environments/environment";
-import {HttpClient} from "@angular/common/http";
+import {HttpClient, HttpResponse} from "@angular/common/http";
 import {Observable} from "rxjs";
+import {Teacher} from "../../DTO/TeacherDTO";
 
 @Injectable({
   providedIn: 'root'
@@ -11,8 +12,8 @@ export class TeacherService {
   private apiUrl: string = environment.apiUrl;
   private http: HttpClient = inject(HttpClient);
 
-  getTeacherByUserId(userId: number): Observable<any> {
-    return this.http.get(this.apiUrl + `/api/v1/teachers/user?id=${userId}`, {
+  getTeacherByUserId(userId: number): Observable<HttpResponse<Teacher>> {
+    return this.http.get<Teacher>(this.apiUrl + `/api/v1/teachers/user?id=${userId}`, {
       observe: 'response',
       responseType: 'json'
     });