Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 646 · 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.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) a mirror (d) lemon juice
2. 2.⚖️ 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 paper
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
4. 4.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
5. 5.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is magnetic (c) it is sticky (d) it is cold
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
7. 7.True or false: cutting the lemon is a job for an adult. (a) False (b) True
8. 8.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
10. 10.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) white paper (d) a battery cell
13. 13.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
14. 14.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
15. 15.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
16. 16.True or false: putting the iron away is a job a child can do. (a) True (b) False
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) reading the message
18. 18.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
19. 19.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
20. 20.True or false: putting the iron away is a job for an adult. (a) False (b) True
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a battery cell (c) white paper (d) a small bowl
22. 22.True or false: writing the message is a job for an adult. (a) True (b) False
23. 23.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) reading the message (c) dipping the cotton bud (d) writing the message
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
26. 26.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) white paper (d) an adult with an iron
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the ironing time (c) the kind of juice (d) the same cotton bud
31. 31.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) white paper (d) an adult with an iron
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
36. 36.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
38. 38.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a cotton bud (d) a mirror
39. 39.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a mirror (d) a cotton bud

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