Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 172 · 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 is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
3. 3.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
4. 4.⚖️ 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
5. 5.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
7. 7.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
8. 8.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
10. 10.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
11. 11.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
12. 12.⚖️ 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
13. 13.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
14. 14.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
16. 16.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) dipping the cotton bud (c) letting the paper dry (d) writing the message
17. 17.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) lemon juice (d) a cotton bud
19. 19.⚖️ 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 iron setting
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) lemon juice
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) an adult with an iron (d) yeast
22. 22.True or false: yeast is needed for the secret lemon message. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same cotton bud (c) the ironing time (d) the kind of juice
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) lemon juice (d) yeast
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) skip washing (d) rub your eyes
27. 27.⚖️ 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
28. 28.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
29. 29.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) ironing the paper
30. 30.⚖️ 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 change it (c) we keep it the same
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
32. 32.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
33. 33.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
34. 34.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) an adult with an iron (d) a cotton bud
36. 36.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) yeast (d) turmeric powder
37. 37.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
39. 39.🍋 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
40. 40.⚖️ 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) the same cotton bud (c) how dark the writing is

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