Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 259 · 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.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
2. 2.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) no, it stays brown (d) yes, in the dark
4. 4.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
6. 6.🛟 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
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
10. 10.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
11. 11.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) heat adds colour (c) the iron is brown (d) paper turns lemony
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) lemon juice (d) a battery cell
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) white paper
17. 17.True or false: letting the paper dry is a job a child can do. (a) True (b) False
18. 18.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a battery cell (d) lemon juice
21. 21.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) ironing the paper
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) it turned into air (d) dry juice is see-through
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
24. 24.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) magnetic (d) musical
26. 26.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) writing the message (d) ironing the paper
27. 27.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron
28. 28.⚖️ 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
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
30. 30.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) plugging in the iron (d) dipping the cotton bud
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) a small bowl
33. 33.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) turmeric powder
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a battery cell (d) a mirror
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
37. 37.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) a rainbow (d) dark brown words
39. 39.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) reading the message
40. 40.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed

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