Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 953 · 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.True or false: white paper is needed for the secret lemon message. (a) True (b) False
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) a small bowl
4. 4.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
7. 7.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
8. 8.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
11. 11.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a magnet (c) white paper (d) a small bowl
13. 13.True or false: ironing the paper is a job for an adult. (a) False (b) True
14. 14.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a balloon (d) a cotton bud
15. 15.True or false: ironing the paper is a job a child can do. (a) False (b) True
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) turmeric powder
17. 17.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a magnet (d) a small bowl
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a balloon
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
23. 23.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) reading the message (d) writing the message
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
27. 27.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
28. 28.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
30. 30.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
32. 32.True or false: letting the paper dry is a job for an adult. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a small bowl (d) an adult with an iron
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) plugging in the iron (d) cutting the lemon
37. 37.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
38. 38.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
39. 39.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) reading the message (d) cutting the lemon

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