Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 921 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
2. 2.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
3. 3.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
7. 7.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
8. 8.True or false: putting the iron away is a job for an adult. (a) True (b) False
9. 9.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) reading the message (d) dipping the cotton bud
10. 10.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
12. 12.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) an adult with an iron
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a small bowl (d) white paper
19. 19.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
20. 20.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
21. 21.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
23. 23.True or false: ironing the paper is a job for an adult. (a) False (b) True
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
25. 25.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
26. 26.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) writing turns green (d) the paper floats
27. 27.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
28. 28.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
29. 29.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a magnet (c) yeast (d) a mirror
30. 30.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: white paper is needed for the secret lemon message. (a) True (b) False
32. 32.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
34. 34.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
37. 37.True or false: plugging in the iron is a job for an adult. (a) False (b) True
38. 38.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
39. 39.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
40. 40.True or false: ironing the paper is a job a child can do. (a) False (b) True

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids