Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 476 · 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.🔮 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
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 keep it the same (b) we change it (c) we measure it
3. 3.⚖️ 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 change it (c) we keep it the same
4. 4.True or false: ironing the paper is a job for an adult. (a) True (b) False
5. 5.⚖️ 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
6. 6.⚖️ 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 paper (c) how dark the writing is
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) turmeric powder
9. 9.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a magnet (d) a mirror
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) a battery cell
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
13. 13.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
14. 14.True or false: writing the message is a job a child can do. (a) False (b) True
15. 15.⚖️ 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 same cotton bud
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
17. 17.True or false: cutting the lemon is a job a child can do. (a) True (b) False
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) a mirror (d) an adult with an iron
19. 19.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) reading the message
21. 21.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
22. 22.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
23. 23.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
26. 26.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
27. 27.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a magnet (d) a balloon
28. 28.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
29. 29.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
31. 31.True or false: cutting the lemon is a job for an adult. (a) True (b) False
32. 32.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
35. 35.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
36. 36.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
37. 37.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
38. 38.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
39. 39.🧺 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) yeast (d) white paper
40. 40.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper

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