Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 622 · 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.🍋 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
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) white paper (d) turmeric powder
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
4. 4.⚖️ 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) how dark the writing is (c) the same paper
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
7. 7.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
8. 8.True or false: white paper is needed for the secret lemon message. (a) True (b) False
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
10. 10.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
11. 11.⚖️ 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
12. 12.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
13. 13.True or false: reading the message is a job for an adult. (a) False (b) True
14. 14.True or false: letting the paper dry is a job a child can do. (a) False (b) True
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) yeast (d) an adult with an iron
16. 16.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
17. 17.🍋 Secret message: who does this step — cutting the lemon? (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) a mirror (c) a cotton bud (d) white paper
19. 19.True or false: writing the message is a job a child can do. (a) True (b) False
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a small bowl (d) lemon juice
21. 21.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
22. 22.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
23. 23.True or false: reading the message is a job a child can do. (a) False (b) True
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
25. 25.🛟 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
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a cotton bud (d) a balloon
27. 27.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
28. 28.⚖️ 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
29. 29.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) letting the paper dry (d) cutting the lemon
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
33. 33.⚖️ 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 ironing time (c) the same paper (d) the iron setting
34. 34.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
35. 35.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
36. 36.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
37. 37.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a mirror
39. 39.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) letting the paper dry
40. 40.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed

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