Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 258 · 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 ironing time is the one thing we change. (a) True (b) False
2. 2.⚖️ 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
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
6. 6.⚖️ 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
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) turmeric powder (d) lemon juice
8. 8.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
9. 9.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
10. 10.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) a cotton bud (d) lemon juice
12. 12.🛟 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
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
14. 14.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) an adult with an iron (d) a mirror
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) cutting the lemon
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) lemon juice (d) a mirror
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
20. 20.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
21. 21.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) letting the paper dry
22. 22.⚖️ 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) True (b) False
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a small bowl (d) a cotton bud
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same paper (d) the ironing time
25. 25.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a small bowl (d) white paper
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
30. 30.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
31. 31.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
34. 34.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) yeast (d) white paper
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
37. 37.⚖️ 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 kind of juice (c) the same cotton bud
38. 38.True or false: ironing the paper is a job for an adult. (a) False (b) True
39. 39.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) a small bowl (d) a battery cell

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